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Why are some 'universal' Windows 10 apps only available on desktop but not mobile (and vice versa)?

Now that we are evidently heading into a storm of new and updated apps for Windows 10, there seem to be a lot of misunderstandings from the casual reader about Microsoft's Universal Windows Platform (UWP).

A lot of this comes down to details of app development that non-developers do not understand, which is fine. It's akin to an astrophysicist explaining a black hole e.g. what Stephen Hawking does in his well-read books. While he "dumbs down" what a black hole can and cannot do based on mathematical theory, the real nitty gritty details are left for those with Ph.Ds. In other words, don't expect to win an argument with him over how information could escape, but why light cannot.

One common misunderstanding over so-called universal apps revolves around why we see some apps on mobile but not PC (think Pandora, until yesterday) or in reverse like Twitter's new Windows 10 app. It can be confusing and that's why we'll break it down for you to better understand.

What is UWP?

The Universal Windows Platform (UWP) is a combination of the Windows 10 OS and Windows 10 SDK. On one level there is a shared kernel, code base and APIs that span everything including PCs, tablets, phones, Xbox One, Internet of Things (IoT), and HoloLens.

This is where the 'code once, release everywhere' mantra comes from and it is accurate in a broad sense. However, there are a few caveats, including:

  • Developers choose where to release an app to. Just because it's UWP does not mean devs are forced to put their app on phone or Xbox if they do not want it there
  • Developers are very much encouraged to modify code to ensure a more custom experience for each platform

The fact of the matter is while your PC and phone may share the same OS the displays and hardware are very different.

Take a PC. The majority of the world's PCs today are non-touch. If you make a phone app that ran on PC and it relied heavily on touch elements using a mouse and keyboard may not be ideal. Things like jump lists and title bars suddenly matter on the PC, but not on the phone. In reverse, a phone app has the status bar to account for, plus vibration, orientation sensors, and more.

Xbox, which has neither mouse, keyboard or a touchscreen, requires a whole different way of thinking about user interaction. Xbox apps are much simpler (think point and click) instead of having a menu-heavy format with an AppBar.

Regarding hardware, phones have a back button whereas PCs do not. Developers need to define and refine how that interaction occurs. Windows Phones have limited memory and in Windows 10 only seven apps can run in the background. Sometimes these apps are terminated based on memory constraints, so you have to handle that behavior too.

There is also the UI and scaling, which are different between phone and PC. While a UWP could just squish onto the phone and expand on PC developers can (and should) take the time to adjust elements for each experience so that it looks and feels right.

These choices assume that the developer cares about the experience, but it is safe to guess that they do care.

Finally, some developers may not want their app on PC and phone – just one or the other. Take what are considered 'mobile only' apps like Snapchat, Untappd, Instagram, camera apps like VSCO and even banking apps. The old way of thinking is either people won't use these apps on a desktop PC, or they can just use a browser. For many, it is not clear what the advantage would be to a Windows app in those environments. Alternatively, you could release a high-performance game for Windows 10 that won't scale properly to a mobile phone (or runs into hardware limitations).

For all of these reasons, Microsoft does not force a developer to make apps for all of their platforms. What they did do is make it very easy for developers to write once and – with some modifications – put the app anywhere at their discretion.

Takeaway

Microsoft's UWP is a step into a new era for developers. The core of the code can stretch to the PC on your lap to the phone in your hand and eventually to the Xbox in your living room.

However, it is still at the developer's will where and when to release. Developers can very easily spend all their time on the PC version of a Windows 10 app, release it, get feedback and when they feel ready update it with the phone experience.

When you are a company as big as Microsoft, working on multiple apps for the OS e.g. MSN News, Weather, Xbox, etc., you likely have one team doing the core coding but have different timelines for features on each hardware platform. One example is how game streaming is in the Windows 10 app, but not for mobile – that needs to be coded and handled differently. Or for Messaging where SMS and MMS is important for phones, but not currently for PCs. These aren't trivial programming matters.

This discrepancy is why sometimes we see different version numbers in the Store for the "same" app.

While it would be nice if programming were literally 'one button' to send everywhere, at least, today this is just not possible. However, as we move to a mobile world with Surface-like devices, the hardware discrepancies between phone and PC will fade. When that happens Windows 10 will be right there to leverage it.

Just remember, a universal app does not mean the app is automatically everywhere at once or that it should be. It is up to the developer to make that happen, and they operate on their own internal development schedules.

Give them feedback, tell them what you want and let's watch UWP grow in the coming weeks, months and years on Windows 10. It is exciting times, but we are still in the early days so let developers have their moment to familiarize themselves with this brave new world.

Daniel Rubino
Daniel Rubino

Daniel Rubino is the Executive Editor of Windows Central, head reviewer, podcast co-host, and analyst. He has been covering Microsoft here since 2007, back when this site was called WMExperts (and later Windows Phone Central). His interests include Windows, Microsoft Surface, laptops, next-gen computing, and arguing with people on the internet.

234 Comments
  • Obviously, this article is keeping things non-technical. So, to my developer friends who work with UWP, feel free to expand upon what is written here with the more nitty-gritty details (and obstacles) in working with a universal app for Windows 10.
  • You beat me to it, I was writing a blog post about this because I was fed up repeating it in the comments here all the time.
  • THANK YOU THANK YOU THANK YOU!!!
  • As a developer working on a couple of UWP apps, I can say your explanation is spot on. I don't think it's necessary to go into anymore detail really as the more technical the explanation gets the more chance there is for people to be confused and start making incorrect assumptions in the comments which then confuses more people!
  • Thanks, glad to hear!
  • You definitely seem like you know what you're talking about. So as a developer, is there any particular reason why Windows 10 for phones can't have two apps open side-by-side the same way people can with a Samsung Note? I've been curious about this for a little while and figured by now it would've been a feature that would've come to Windows phones.
  • @bjax, while I don't have any inside info for the plans of Microsoft, I believe this is something they are working on and would likely fit well with the Redstone update next year that is rumoured to have the continuum improvements. As I always say at work, anything is possible in code, however, I agree with the approach Microsoft seems to be taking for some of the features like this, and that's to think it through carefully and make sure they get a great experience. It wouldn't be good to see them cram it in early and end up with a sucky experience.
  • That's true...i suppose that's probably why Windows 10 mobile hasn't officially been released to other phones yet- they're still tightening it up.
  • I don't understand where people got the idea the upgrade was going to be availible right away, MS always said January in all their timelines for upgrading the old phones.
  • Just out of curiosity, how do you even use 2 apps side-by-side on a 5" screen?
  • Yeah,now that you mention it, I think it's more top and bottom with The Note. But far as doing it on a 5" screen...idk...that feature is only available on Notes I believe, so I guess it would have to be a similar situation, only available for screens larger than 5".
  • Makes sense
  • my 4.7 inch phone has top multi window support.
  • Mostly do it to watch video and tweet or message in a separate window. But my screen is larger than 5". BTW works on LG phones too. Though you can also have a third window ontop if you really wanted with transparency even. Haven't found much use for it though.
  • +1. One thing I'd like to add, as another UWP developer. There's one more reason why a developer may decide to limit his UWP app to mobile only. If he already has got a classic Windows desktop software, then he may find it redundant to have an app with similar or limited functionaliy in the Store.
  • One key thing that is needed (not considering UI and UX considerations mentioned in your article) is the requirement of an ARM compiled package. If you're using an external dependency that cannot compile for ARM, that will stop you in your tracks. However, 99% of the time, it only requires a simple References > Add > Mobile Extension SDK in order to get an ARM package and publish for phone. Note: Personally, I found that it doesnt require alot of work, BUT it does require work and testing.That is usually the cause of the delay between PC app and mobile app releases.
  • This is kind of too technical to be added to the post, I guess.
  • a good example would be VLC, it's on the phones now, I'm still a little amazed how they were able to do all that in about a year and a half
  • But VLC is not a Windows 10 Universal App.  It's using the more complicated Windows 8.1 'universal' apps.  So they actually had even more work than described here.
  • oh details, details... lol it makes it even more amazing what they've achieved no? ;)
  • Too technical. Let's put that on the stack for now and pop it later for another appropriate discussion.
  • Something that is important for people to understand is that there is a difference between an 8.1 "universal" app and a UWP app. And there isn't a big switch to magically go from an 8.1 app to a UWP. Even if there was, you'd end up with a horrible app that doesn't take advantage of all the new stuff in 10. So be patient with developers that are updating from 8.1 to 10, it won't happen overnight.
  • They took the time to make a bridge to go from rival platforms to W10, but they didn't do it for their own, you say?
  • It is possible, but takes some manual effort. Just like the bridges for iOS do. The big magic button does not exist unfortunately.
  • There is one, It's called Visual Studio. It uses the same tools, well the newer ones, but the App developer needs to change up things to reflect the changes in UI/UX
  • Ever heard of App-V containers? That's the bridge to wrap Win32 applications into something that can be easily installed/uninstaleld via Windows Store or App List. No more MSIs to worry about. That's the bridge for legacy desktop apps.
  • This is something that had me wondering for some time now: how Universal Apps for Windows 8 and 10 are the same or different.
  • Windows 8.1 Universal apps allowed a lot of code sharing, basically you would have 3 projects one for Desktop, one for Mobile and one for Shared Code and resources (icons etc..), anything that would be the same on both platforms would be put in the shared project, however this still involved having 2 distinctly separate projects for Desktop and Mobile. Under the Windows 10 UWP, the same thing can be achieved with a single project, and while not mandatory the apps can share the same UI code with adjustments made for different screm sizes and different input methods, you can think of this like a website that automatically changes based on your screen size with content moving around and resizing to suit. With the vast improvements to UWP over Windows 8.1 universal, many more APIs have been moved to the common core framework (OneCore) which makes it a developers dream.
  • I have always thought that the limited APIs (that I heard about but I am no developer) was a big reason why WP apps never really took off or got developed in the first place. Is that assumtion accurate? And if it is, does the UWP for Windows 10 provide enough that more developers and first party developers will develop for the platform? On a side note, I have thought that Windows Phone devs were some of the best devs out there. I prefer several YouTube apps and Twitch apps over official ones on Android and iOS for example. And also a few that brought Steam chat to my WP8.1 =).
  • Generally speaking - yes, API in per-Win10 era for "universal" (or "modern") apps was (and until we'll have Windows 8, 8.1 - still "is") much more limited. Now things gets better. At least it looks like a start in right direction from MS. Crossed fingers.
  • This has been a problem in the past, however, Windows 10 is starting to open up many more APIs than previously possible. The UWP is still no match for Win32 if you need to dive deep under the hood and do some serious processing, however in a lot of ways this kind of model is now obsolete and there are other directions you can take, for instance you could perform processing on a server and expose the data via an API and then have your UWP app connect to that API and have a great user experience compared to a traditional legacy application full of menus etc. UWP still has a long way to go, but personally I think it is already fantastic and you can do a lot of cool stuff with it.
  • @mbrdev, thank you so much for your valuable comments. Can you explain this post a bit more. Am I understanding incorrectly, or is this correct: you are saying that since it is not possible to do in UWP everything that you can with Win32 API, you can somehow do it on a server. I am don't see how. Can you please explain? Also, is the expectation that Win32 will be completely replaced? Soon?        
  • @mbrdev Thank you very much for this explanation.
  • No problem
  • I hate websites that resize because I'm using a mobile. I have selected "desktop view" in my settings so I want to see the desktop site on my screen. If I want to view the mobile site I'll change the setting to mobile. I'm a big girl, it's my choice to make.
  • Universal apps in 8.1 were mostly code sharing between two (or more) discrete apps that shared an "app ID." For phone and PC, you'd have three projects: A phone app, a PC app, and a shared library. Universal apps in UWP are one code base compiled to any number of Windows platforms. You have one project, one app, many targets.
  • Kind of annoyed that it's always "lazy developers", etc. when it is never up to the developer, even in the case of single developer indies, it's the CEO-side of the person which decides these things.
  • Agreed, however, when I say something like "its up to the developer" I'm actually referring to the company that develops the app in most contexts. It is very true that in most companies developers have very little input into what they make, we are given projects and tasks with strict requirements and usually unrealistic deadlines. In some companies developers are seen as a "necessary evil" because we are not seen to make money, it is the sales and marketing departments that "make all the money" amd as such some CEOs put no focus on development departments at all so we have to put up with limited funding and limited resources while still trying to produce quality software.
  • The simple, easy to understand article that Microsoft doesn't want the general user to read. This basically reveals that it's not that simple. One app everywhere just does not exist. Even though their entire advertising campaign says otherwise. Brilliant business strategy though.
  • @eddp77 No, you are twisted. You can have 1 app to run everywhere. In order for there to be one app, you need to modify your XAML (the bit that draws the screen) to include "view states" that expand and collapse at different resolutions. Some developers, don't want to, don't need to, don't care to, make their XAML work on any type of screen other than their chosen target (phone or desktop mostly). Or, they have developed their app for Desktop, and will think about changing their XAML later to accomdate phone for example. So stop dissing MS. The tools are there. 1 app that runs everywhere is possible. Some devs chose not to, or, are doing one device first and another later.
  • Exactly.
  • Im not twisted thanks. My point is that MS is pushing the one app everywhere ideology. Whether or not devs do it is not my point. Im not "dissing" MS, I'd go as far as to say im a big fan actually.
  • I understand what you're saying, but there are some considerations:   1. A developer should be given control over whether or not they want their app on a specific device. For example, even if Whatsapp makes a Windows 10 SDK based app, it will not be allowed on desktop. (Purely speculation based on their policy on other platforms). The app is still built with the universal tools (Microsoft and developers are referring to the entire Windows 10 platform as the UWP or Universal Windows Platform) and is a "universal" app that runs only on one type of device.   2. Yes, there is built-in support for automatic scaling and I can develop an app by just dragging a button on the screen and hitting 'Build'. It will work perfectly as a Universal app on *all* supported Windows platforms automatically. In real-world scenarios, however, apps are more complicated than just a button, so I would have to assign a UI to each device. After all, the desktop UI cannot be just made smaller or "cut-off" on the phone. It is super-easy to implement separate UIs but I may not want to do it.
  • Was just about to explain your second point but you've beat me to it
  • Had to know someone would come and muddy up something that was made perfectly clear.
  • Microsoft only markets the 'one app everywhere' TO DEVELOPERS... not to regular consumers.  So you're obviously confused.
  • It is up to developers whether they want to support phone.  But it is up to us whether we want to purchase the UW apps that don't support phone.  I would avoid those apps if all possible for the Continuum sake.  I have been keeping track all the new announcements for UW apps in the last few months.  The number just passed 200.  It is not that many but it is a good start.  The pace of releases should pick up with the increasing W10 installs.
  • Well, really UWP helps to bring the same App everywhere, you can do it, if you want, and is complicated, like any app development, but is possible. 
    UWP is removing a bunch of differences between platforms. Now you can start working on your app, and most of the elements you will use are Universal (meaning they work on any of the platforms.), it may look horrible in some devices, but will still work, without any changes. Once you hace that, the you can "prettify" it for each platform using adaptative UI techniques, and increase UX (User eXperience) on each platform by taking advantage of each family specific options.  So, is not only marketing, UWP is pretty awesome. 
  • One app everywhere actually does exist, so long as you would be willing to put up with a half-baked UI/UX. Microsoft can't create an algorithm that can automagically develop every application for every developer for every use case. The variables are far too great. The API takes a guess at it using basic design guidelines, but it is up to the developer to tailor the UI/UX by device type and to enable functionality by device type. Not all hardware is equal.
  • Wow!! Thank you Daniel!!! Amazing explanation.
     
  • Can we just link to this whenever someone says some snarky remark about "universal" not being "universal"?
  • Great explanation - thanks! I think some of us non-developers may not appreciate the complexity of dynamic layout - especially if you think about a mobile app that can dock with continuum and become a desktop app. UWP makes it easier to for devs to target multiple platforms, but there's still work for each screen type to be done.
  • The whole paradigm of "write app once and run it everywhere" is very appealing, but mostly because it's neglects the fact that you still: 1) always have to write code to deal with different screen size - with PC and its free windows resize you may technically end up in something known in HTML world as "responsive design". 2) test the app with different devices and not only because of the screen size difference, but also because of performance considerations 3) maintain the app for different devices (yep, some issues still happens only on specific devices because of some third party drivers issues) And this is not to mention possibility of usage some platform-specific API - yes, now things way better then before, thanks to MS, but there are some work that needs to be done by developer to handle it correctly. So, when you hear "universal app" - consider it as "mobile app + destop app" just in one package which seamlessly flow from one to another. Taking this into account may help understand why first versions of some apps supports (or "target" in Store) only one platform - desktop or mobile, depending from where their business comes from.
  • Awesome article
  • great article. one thing i would contest (and think many companies just have not realized yet) is that the "people just use the browser anyway" approach is not really valid. not that you said that but it is one point that repeatedly comes up in conversations about universal apps. yes, people use the browser version of a service on pc but only because there are no alternatives in many cases. i personally prefer netflix app over the browser experience, the same goes for twitter, other streaming portals etc. the only reason why i do not use facebook via app is because i find the app experience lacking. personally i would instantly switch over to a banking app from the current browser option. if done right - livetile and all - apps can be way better and more efficient in almost all situations than a browser. just as an excample: right now i am regularly annoyed by e-mail notifications from my bank that require me to log in and check if whatever they want to talk to me about is of interest to me. via app they could push the notification to the live tile on my pc instead. on opening the app i directly get to the information and can dismiss it. they could also use the notification center to divulge essential info directly (with respect to privacy of course). there are tons of options here, companies simply are stuck in their old ways and can not see the potential it seems.
  • Great article Daniel.
  • Its not a myth at all. There is still a single, reusable codebase that will run on all W10 devices. That is not something we have had until W10. For a developer, its much easier to write an app for all windows platforms now than it ever has been. No, it doesn't automagically do EVERYTHING for you, but it makes it as easy as possible.
  • I don't understand how you could arrive at such an incorrect conclusion.
  • Thanks for the write up! I have to say well explained!
  • Should have just called then windows 10 apps and used the "universal" terms for apps that are released on mobile/pc etc
  • It kind of is that way, Microsoft generally calls them just 'Windows apps' and 'UWP' is something for developers. But yeah, even Microsoft flubs that and they called Netflix 'Universal' too.
  • Thanks for the article. Explains why there is no new twitter and shazam app on phone though they are universal apps.
  • I think they called that Netflix Universal because they know there's phone version coming.
  • Yes. They refer to the entire Windows 10 SDK platform as the Universal Windows Platform. Being a universal app in the sense of being available across multiple devices is another thing and is separate from being built using the UWP tools. Good article.
  • It is universal, they've just not released it for mobile yet, likely still working out the design. But my guess is all of the core functionality has already been written and is being/will be used by all device types. Code once run anywhere. And even the UI/UX will likely exist in a single project, unless Netflix chooses to break it into multiple projects. It's effectively a bunch of if/then statements built into the XAML framework with relative panels and such. If this screen size, then this layout. If this device, then enable/disable this functionality, etc.
  • Exactly!!
  • And then everyone would be asking if it is only for PC since windows10 is not windows10mobile :P
  • If they don't say UWP apps then folks will wonder why some new windows phone apps are not enabled for Continuum. Additionally, continuing to say Universal is also a great marketing approach to have everyone believe that it is best to get a windows device given that the same app can run on all devices (yes the article address that this is not necessarily the case).
  • Thats pritty obvious:/
  • You'd be surprised. Many people need this clarification.
  • Trust me it's not.
  • Some things are more apparent than others. E.g. Spelling ;)
  • Would developers riot if MS starts to force them to make phone app at the same time as PC?
  • If it didn't make sense for their app to be on both they would completely ignore the platform. The way it has been done is perfect, it makes developers lives easier and makes apps more profitable if they chose to go on multiple devices (By more profitable I mean the development cost would be lower than if it was a separate core and needed completely seperate apps per device)
  • Not sure if thats a right word but yeah, something like that. Developers wants and needs something that helps to make devlopement easier yet giving them flexibility so that theg can do what they want. Forcing it just making things uncessary complicated and even this article stated that not all kind of apps are applicable to have multiple form-factor support or simply its just way too technically difficult to do. Microsoft needs less barriers for developers to develop and invest to their platform.
  • If MS forced devs to do this, the users would riot becuase of all the crappy poorly optomized apps out there or there wouldn't apps out there in the first place.
  • An awesome article so non-techie folks can understand. The images and commentary are exceptional. I am a techie but appreciate how well this post was written for ALL to understand. Great work!!
  • Thanks, hopefully it'll resonate.
  • Daniel do you know anything about the windows 10 mobile version of twitter ? Posted via the Windows Central App for Android
  • I think it will sink in generally. The article has explained a lot to me. I'm not a programmer but now have a sense of complexity on this, business scaling and human nature. Aside from W10 devices I'm a big fan of my Macbook Pro. At some point I'd like to jump to a Surface Pro, but I don't think I will. That's partly down to having collected a fair amount of costly Adobe CS software. But I also really rate the newer, much cheaper Affinity series. Affinity have no plans to do Windows versions. They don't want to expand the firm, so concentrate solely on where they have momentum. That's frustrating, but taken from their view it's also shrewd. They're craftsmen, not a production line. I'm fine knowing you can't have everything but appreciate Microsoft for being accommodating.
  • Your Adobe CS licenses can be used on Windows as well.
  • Thanks Antny, yes that's true for my Indesign CS6 license. But Adobe won't for full CS3. Throw in Affinity's growing, better software and it's an issue. I complicate matters as I also don't want an Adobe CC subscription. I do really rate the Surface Pros tho'. Thanks.
  • Sorry, thanks BaritoneGuy.
  • If devs like snapchat can't make app for our mobile platform then they should allow third party devs to make client app for us.
  • Snapchat was hacked so they killed all 3 party app, but I hear they are looking in to it
  • You should forget about snapchat, the CEO is completely anti Microsoft
  • No. He is anti-EverythingNotApple
  • But there is an Android version
  • Which is constantly buggier than the iOS version even though it has the most users...
  • That's pretty standard for a lot of apps on Android.
  • Thank you for explaining this.
  • The problem really stems from how Microsoft marketed and hyped it as code once and run everywhere, cant expect everyone to have a developer-level of knowledge, they set the expectation themselves so no surprise people were confused when it didn't seem to work as seemingly advertised but anyone who has followed Microsoft should have known they always massage the truth in these claims....
  • This!!!!
  • Did you even read the article?? IT IS THE SAME CODE. IT IS THE SAME CODE. IT IS THE SAME CODE. Got it?
  • You're good at explaining things lol....oh wait.
  • Lol I'm not sure what else to say... I've explained it on multiple articles and now there's an entire article explaing it, and people STILL say "But it's not really the same code...."
  • @theefman, you are exactly the person this article was intended to educate, but you seemingly failed to grasp even the most basic concepts from it. IT IS, CODE ONCE, RUN ANYWHERE. The apps are perfectly capable of running anywhere, but devs chose not build their XAML to include both device states and select only phone or desktop in the store to publish. MS are not massaging the truth, go read the article and get educated, as you are simple wrong.
  • It could be a lack of understanding when you say "code once...chose not (sic) build their XAML." I have no idea what XAML means so the rest of what you just said is gibberish to me.
  • Replace XAML with User Interface(UI)... Im just trying to help... so it would read "but devs chose not build their UI to include both devices and select only phone or desktop in the store to publish"... The app, by default will run on all W10 devices... its just that if the default UI if allowed to run will be useless on most devices... so since quality of experience directly affects developer reuptation... devs choose to build the UI for only few or one device type..... until they have tuned it for each device or ... choose not to "build UI" for some device types as it is irrelevant for the app.
  • Think of it this way. Let's say I develop a calculator app. One of the things I need are buttons for numbers and functions. With UWP I only need to create those buttons one time. Those buttons will be used for whatever device family I want to target. The UWP API will automagically scale my buttons to the screen size. They call it relative pixels. For example, something that I've designed to be 20 pixels large on a mobile phone, will be proportionally scaled even if I'm using an 80" Surface Hub. But it's the same button, I developed/designed that button one time, and wrote the code one time. What the developer has to decide is what if anything should change on different device types. Just look at the Windows 10 calculator app on desktop versus mobile. It's the exact same application, but you'll notice differences in layout, element sizing, what functionality is available on screen, etc. But it's all the same app.
  • The problem really stems from how Windows Central visitors apparently can't read. 
  • You win the Internet today. (@theefman above is a classic example of this inability to be able to read)
  • @corvodun: LOL! Good one :D
  • Let's say there are two things that make a software, the GUI and the code. And the business logic needs to be coded only once. Then, i think, the developer has the option to design a GUI for each device/screen size. And the developer can choose which ones will be deployed to the store. I suppose, the developer can design one GUI and let it run on all screen sizes, but then we will all complain about that too.
  • +1 Good example: the recent "Breaking news" app... the UI is so ugly on a windows 10 desktop, it's made for phone, not landscape screens...
  • It is Code Once Run Anywhere, its just not 100% automatic. There has to be some effort on the layout and UI side for each form factor, but its WAY easier than starting over and submitting to different stores, etc. Some apps dont make sense to run everywhere - like there's no desktop version of Uber. Uber needs to be running on something with you, in your hand or pocket, not back in the office on the desk.
  • Microsoft only marketed that TO DEVELOPERS... they didn't promote that to general consumers.  Why would general consumers need to know that they can code once and run everywhere?  It's FOR DEVELOPERS to know so they can improve or bring their apps into the WIndows platform.  Gosh... some people think everything posted on a fan site is marketed by Microsoft to everyone.
  • The more you know
  • So your saying the Devs still need to discover the part where a Relativity app meets a Quantum app before they can build a app of everything?
  • As long as the developer won't caught up in the singularity in the process. Lightspeed is the limit.
  • I was more worried about being able to shut the quantum apps down as the little blighters seem to open in multiple places at the same time. They may have to add a new face button...
  • You can get around the light speed limitation by tunneling through subspace.
  • So the next big thing will be the wormhole apps.
  • Snapchat is available on an iPad.  So are banking apps.  So these days the tablet/mobile is very much the same.  Which really means UWP apps should be released for mobile and desktop (tablet) users. Rarely is an app purely mobile phone only due to the mobility of tablets.
  • In windows world a tab is actually a pc.. By which i mean we have keyboards and mouse to handle..and also more firepower and more options on a developer level.. So its not same as an iPad coz at the end its same as the iPhone with larger screen.. You cant connect every peripheral made for mac to it.. But in windows it is there
  • You're right. Even my 8 inch Windows tablet is a million times more versatile than an iPad. I can hook up any PC accessory I want.
  • You are right, with Windows, it is a little more complicated. PC can be a 8" tablet with GPS and the ability to make phone calls, a laptop, or a traditional dekstop in the office. An iPad is always an iPad.
  • Actually, snapchat is not available on the iPad. It's just Apples way of forcing iPhone apps on the iPad. Same with android. You cannot choose if you only want the app on phones. If you could, snapchat wouldn't be available on Tablets.
  • Messaging apps originated on the PC. Many people still use chat and messaging from PC. I don't understand why people think something like Snapchat should only be for Mobile. There is a market, waiting to be had that ignorance is blocking.
  • I agree and W10 is ideal for this. Messaging should be everywhere you are. Working on a PC, Laptop, Tablet, Phone - I want the same service everywhere. Facebook is probably doing that better than anyone right now.
  • Snapchat is not really an ipad app, but you can run the iphone version on your app (with zoom)
  • An exellent article!!! Well written and understandable. Well done Daniel. Now I just hope everyone understands how the Universal Windows Platform works​.
  • But the best part about UWP apps is that it requires a single packaging. So, the app may not be available on some form factor due to lack of optimization, but at any point, should the developer choose to bring it to any other form factor, they won't have to start from scratch. They just have to modify the code already written for app and available on windows store to optimize it for desired form factor. And it's a cunning ploy on Microsoft's part. As a developer, I may decide to optimize my app's existing code to run on all device types and screen sizes once and for all hoping it might take off somewhere.
    Then again this might be wishful thinking on my part, hoping so desperately for it to succeed and be adopted by developers and OEMs alike. Because it's my favourite platform and platform of choice for my computing needs.
  • Yup, good point.
  • And the beauty of the idea is that as devices change over the years, as they will, ideally you won't have to re-write your core code, except maybe to handle new hardware capabilties, but instead will just have to add UI/UX focused stuff to handle say HoloLens or whatever. Updating could be incredibly easy.
  • Another reason for developers not releasing is because some of the API's (in my case media casting) do not function correctly on mobile compared to the way they run on desktop. In fact this very reason is what is delaying my windows 10 UWP app.  UI improvements and adaptive screen sizes also mean a lot more time needed to adapt their current app to make them look and feel as the user expects.
  • Excellent point.
  • Is that the reason (or something similar) why the Windows Central Universal App isn't ready just yet? I may have missed any updates you've given on the progress of the app.
  • @Ragbuster. Can you be more specific on the API (media casting) you cannot get working or find? But true that devs need to create the adaptive UI with viewstates and triggers. XAML can be a nightmare to layout controls at times :/
  • @hwangeruk The main issue is that when using mobile and casting audio to a dlna device eg, windows media player or receiver the media ended event never fires, works fine on desktop though, could be phone bug or an issue with SDK but not certain, still waiting for some sort of recognition of this problem from Microsoft.
  • Totally agree. A lot of DEVs were waiting for the 10586 build to be availble for Windows 10 Mobile, for the want of better stability, and enhanced API support. The Universal Windows Apps subsytem got upgraded to v1.2 (for the developers audience who want to know) with the relase of 10586 build, and brought together better API support and removed a few restrictions on  phone APIs.
  • wow...tone of the opening paragraphs seemed a bit condenscending.
  • I don't think so at all. I've seen news articles literally about Hawking's new theory on black holes and people were debating it on comments. Sometimes you have to know your limits. App development and being a consumer are very different things, yet consumers tend to have an uninformed opinion about how these things work. That's not blaming them, they should not be experts, but it is my job to help bridge those two communities. Regardless, it was simply an analogy and if you read the comments on the Netflix post from earlier today, you would see where this article's theme was coming from.
  • The article was good; I found it a little patronizing too. But there are many people who needed to be explained this, so I think I can ignore that.
  • Great article Dan, I like the way you "dummied" it down. I am a software engineer and have been developing with UWP since its release.
    Choosing the platform to be able to deploy to is as easy as selecting options. That's the easy part. The part that makes the difference really comes down to the UX - user experience. The easiest way to handle it is by using states and their triggers in the XAML. All of the actual functionality can stay the same, unless of course you are doing something specific for a device, i.e. make a phone call.
    A simple resize of the elements is not always the best result. Shifting things from being side by side to being on top of each usually is best, especially if you want singe sort of interaction with touch.
    There are so many different things to discuss, and this is not the proper venue for such discussions. I do like the goal of the article as to try to explain somewhat why you notice the discrepancies.
  • Nice, thanks for the input and agree, I hear the UX stuff is where the tinkering is needed. Appreciate the info.
  • Great article, nice way to put things up.
  • MS needs to make more of an actionable buttons on all systems. Digitally or not. We need a back button... Oh wait charms... Could have added that there...****. Charms should just have moved to the start bar...
  • Actually, if you push Win+Backspace, it triggers a "BackRequested" event within the app, and assuming the app is able to handle it (this specific event was introduced in Windows 10 so most UWP apps should), it will have the effect of pushing the back button on a phone.
  • Try it out in Microsoft's apps
  • There is  a back button in UWP, that uses the hardware button on phone and switches to a menu bar back icon in Desktop. Its all done magically for you by the tools and runtime.
  • You have a back button in tablet mode. If you're not in tablet mode, there is an optional back button MS provides that the dev can enable that acts the same as the phone back button (I do this in my own app)
  • Thank you. This was a great write up and should help folks understand why, for example, Netflix didn't come out for the phone today!
  • Mobile is for now the only game with apps. Even Apple with religious fan base has noticed that. Nadella needs to win mobile but at least for Windows he has given up. PC first won't work.
  • Every computing tech will reach a threshold at some point. PCs did. So did iPads and Samsung. The only reason iPhones are still going strong is because of a phablet space they were previously missing and their slow rate of hardware upgrade like core nos or camera megapixels or RAM or storage and so forth. That and carrier subsidy. Phones are just easy to upgrade than tablets and PCs because of carrier subsidy. But carrier subsidy looking to dwindle in states and mobile hardware fastly approaching a threshold, you could expect smartphone sales to start slumping in a few years. Except continuum. The soul behind continuum is the future of mobile computing though it remains to be seen if Microsoft may succeed in it or gets beaten here too by likes of Apple and Google even though Microsoft was first with this idea. I expect Apple to fully embrace this idea despite whatever Tim Cook says about converging its OS's(hint: IPad pro which is incomplete without MacOS x86 applications). Even Google realizes this with their recent entry with Google Pixel C and rumors of chrome OS and Android merging but luckily for Microsoft, Google faces the same x86 applications gap that Microsoft faces for ARM apps. But Microsoft will overcome ARM(native) app gap before Google will ever overcome x86 applications gap. And honestly, we know x86 applications ain't going anywhere for a foreseeable future. Though, with ARM closely catching upto x86's power while retaining the battery efficiency it is famous for, Microsoft do need to act fast on Project Centennial( a bridge to bring Win32 apps to windows store, for now, but, which I really imagine needs to optimize existing Win32 apps for both touch & ARM and also for multiple device types and screen sizes for this idea of UWP apps to work), if they know what's best for them to protect their rule on traditional and professional computing and PCs.
  • Although coming to think of it, Apple may actually not be thinking of merging iOS and Mac OS at all. They may be fully gunning their hopes on iOS going forward. Apple is the only ARM licensee which is increasingly showing the prowess of ARM(apart from NVIDIA with their Tegra chipsets) as a hardware and with increasingly number of productivity apps on iOS(creative arts, photo retouching editing, filming apps, music creation apps, so on and so forth), their demonstration of what ARM hardware can do with right software in iPad Pro launch, and their pull with developers, Apple might actually succeed in bringing the traditional x86 ecosystem to iOS and Apple store in coming years, which they could never do with Mac OS in face of competition from Microsoft's Windows. With their already tight integration of designing their own chips to having their own platform, the advantages it brings in speed, fluidity, optimization, benchmarks and stability; Apple may actually be gunning for the top spot. Something they tried with x86 and Mac OS but failed against the likes of Intel and Microsoft's Windows. And as a Microsoft fanboy, this train of thought is scaring me.
  • As you say IOS & Android were developed for toys and are reaching the limits of what they can achieve, Microsoft is aiming for the high ground in the portables, the professionals who realize the ipad pro is no more than a giant phone the iphone is just not possible to use in any business, I have no doubt that in the near future x86 is going to springboard Microsoft into a huge lead when it comes to what you can fit into your pocket. Then apps will be called programs again and win 10 will have 100% adoption because it already has it. With android having nothing to compete and Mac Os being well the less said about the HFS+ system the better I cannot see Microsoft failing not with a man like Nadella heading it up... In 2016 everyone will hear the world over, the Microsoft battle cry of 'Release the Panos!" Steve jobs must turning in his grave like a turkish kebab...
  • The 2.5 billion visits to the Windows store since the release of Windows 10 don't agree with your statement. They can't all be by accident.
  • Okay coming back to read your comment again, I have to agree. Yeah, mobile is the most user friendly platform for apps. But as long as we continue to use PCs and tablets, I'd rather have a native app experience than a browser experience(which in my case hasn't been all that great in all my years of computing). So there is that.
  • NOT FOR PROGRAMMERS!! :) (It's too oversimplified)   I'll just add a little personal experience here to add to the article. In an app I was building I wanted to reload the project list when the user navigated back to the home page. Now, I was storing my projects in what's called an "Observable Collection." Think of it like a jar (the Observable Collection) that can hold marbles (the projects). This all worked fine and dandy on my PC. However, it consistently crashed on my phone. To make a long story short, I finally realized that, because of the back button on the phone, the function that cleared the project list was getting run twice, causing the app to crash. This would be like telling you, "take all the marbles out of the jar," and once you've done it, "Now take all the marbles out again." Obviously you know that there are no more marbles to take out and can tell me so. But a computer will crash when trying to do this. Anyway, hopefully that gets technical enough without getting too technical. :)
  • Hah, well considering I am not a programmer (though I did consult one for this article) I agree, definitely simplified :P Thanks for the real-world example, helps to put into perspective!
  • And I guess you need to know which size jar you put your marbles in.
  • if(MyObservableCollectionOfMarbles == null) { return; } at the top of your ClearTheMarbles() method will fix that.
  • Lol no, it was a bit more complicated than that due to some other stuff I was running. :) As I said, the example is waaaay dumbed-down.
  • @Esbe, it really shouldn't be complicated though: In your Home page: public MainPage()
    {
    this.InitializeComponent(); //Clears the back button. Not needed on home page
    SystemNavigationManager.GetForCurrentView().AppViewBackButtonVisibility = AppViewBackButtonVisibility.Collapsed;
    } Then in your actual sub page: protected async override void OnNavigatedTo(NavigationEventArgs e)
    { currentView.BackRequested += SystemNavigationManager_BackRequested; } //Below needed for back button
    private void SystemNavigationManager_BackRequested(object sender, BackRequestedEventArgs e)
    {
    if (this.Frame.CanGoBack)
    {
    this.Frame.GoBack();
    e.Handled = true;
    }
    } My invoice is in the post ;)
  • You're right, if that's all I was doing. IIRC the exact issue wasn't even that it was double-clearing. I don't remember the exact problem, but you know how programming goes... It's never as easy as you think ;). I just gave the double-clearing example because the actual problem, along with all the variables in other classes, etc. that influenced it, would have taken a whole essay to explain / parallel, and double-clearing was close enough.
  • Just went back and looked at the actual code... The issue was that I was trying to unload the current project, and I had missed an e.Handled = true; So my example was... kinda close ;). It was an easy fix, but it still stands as a reasonable example either way, I think.
  • Right now when you develop an app for windows 10, the only choice is Universal. So yes, all windows 10 apps are universal at conception. A developer will usually start designing the UI for one family of devices or another. Even if the intent were to use relative spaces on everything in the design, there will still definitely be changes that will need to be made for the app to function or look correct on other device families. Posted via the Windows Central App for Android because I am unfortunately with Sprint
  • Well in reality there's no reason to think the project options will change. There's no reason for them to.
  • As a dev, I can say excellent article; technical enough, but not too technical. If people don't get it after that, they don't plan to.
  • Also, I hope cheap Intel atom based tablets running windows 10 become mainstream. As for developers questioning the demand of native apps on tablets/PCs need only read and view the reviews of Google Pixel C which is getting thrashed for Android OS and Android apps not being optimized for large screen tablets. So yeah. If people prefer native apps over browser in phone, they will also prefer native apps over browser on tablets and laptops. Native apps just give far better experience than web will ever give. And as such, companies and services need to start focusing on improving native app experience over web. And that means optimizing it for windows based PCs and tablets (and windows phones too, as a positive measure). Wink wink.
  • Yes. A cheap $100 tablet with Windows 10, 2GB RAM, and 32GB storage. Put a 64GB card in since apps can run on SD card. Best value ever.
  • I even prefer some apps on a desktop. I had quit using Pandora until I got the universal app yesterday. Now I'm completely enjoying it.
  • So its like the iPad iPhone store. Some apps are optimized for tablet and phone bit not all. Duh
  • Very well written. I am currently working on UniShare for the UWP, and I have to say it is very convenient to write the code and test it first on my PC, then just fix the visual things for mobile. Making good progress here. :)
  • One way to help devs consider "Fully" universal apps is to give credit to the ones who do a good job like "Home Automation for Lightwave", "Huetro for Hue", "Fitbit", "TVcatchup" and "Demand5" to name a few that I use regularly on PC and phone. And then ask other good app makers to consider making their good app even better by becoming universal for example I found "English Dictionary for Windows Phone", really good app on the phone, I would love to have the same app on tablets and would even use it on the desktop PC, so taking my own advice I will give them some feedback right now.  
  • You didn't mention my app :'( . Jk. I agree there. The "5 intriguing apps" article does do a little bit of that.
  • I just want a universal Spotify app as my life depends on that stupid service way too much :/
  • Thank you! This has, indeed, confused me. Your post has brought a little more clarity to the issue.
  • Is there even one app that currently runs on phone, PC, tablet, laptop, Xbox and Hololens? One app, everywhere? Or is there not even one developer out there, including MSFT that finds it worth it to be everywhere?
  • I am just waiting until Microsoft lets me add UniShare to the Xbox one. Hololens is another thing, but I was already thinking about it, tbh... ;)
  • Well so far I've put mine on phone, PC, tablet and laptop. Don't have an Xbox or Hololens.
  • If there is or will be one, it's probably Plex. That one is already on all platforms (apart I guess from HoloLens but HoloLens isn't a commercially released product so it's irrelevant for now).
  • "Is there even one app that currently runs on phone, PC, tablet, laptop, Xbox and Hololens? "
    Baconit and Edge. Likely others, but until devs get hardware to test on, it's a bit difficult to evaluate. Same with Xbox as that store does not open until 2016.
  • Wrong: PCs due have a back button. It's at the top left in the tile bar or at the bottom in the task bar (while in Tablet Mode).
  • Wrong: PCs don't have a back button. Apps have the back button. Different things.
  • You're both right! Windows 10 PC no back button Windows 10 PC in Tablet mode...back button.
  • win+backspace
  • Okay and what about the twitter app ? They don't want to release the mobile app ? And they are Microsoft partner , i don't understand why all this delay Posted via the Windows Central App for Android
  • The WP Twitter app has a far far better design than the Windows 10 app. If I was still using WP, the last thing I'd want was for the W10 app to replace the one currently in the store...
  • It is missing many features , but i don't understand something, they released the pc version in august and till now they didn't release the mobile version!! If they are writing a complete new app it would be done Posted via the Windows Central App for Android
  • They are probably still working on the UI so it scales well on mobile devices... or possibly they are focusing more on bringing all their features on par with iOS/Android and finalizing that UI before making it scale for Mobile. But really they should be designing for Mobile first (just like responsive websites).
  • Oh I had asked a question about the same thing in the Netflix article and see what explanation have I got :D
  • Still have not seen one original, powerful or great app,, all these universal apps are old news but I guess for the last few Windows users this is a good thing but i still dont see the developers caring to make an app for windows mobile or windows its all about the Apple
  • Novelista. FlipPad. AppRaisin. What the sam hill are you talking about?
  • Yeah tried those apps not impressed at all but novelists is a great idea overall but after checking the app store looking for games we need some big name apps period the **** you talking about?
  • Thank you for this article.  I was one that was very confused by this.  When I hear the word "universal" I think .....universal, or everywhere.  So when a "universal app" wasn't everywhere, I didn't understand. Now it makes more sense.   
  • Cheers, glad it helped!
  • Thanks Dan, the article helped me understand the UWP more clearly. A good example would be Netflix who updated their app for Desktops/Laptops and Tablets but the Phone version is still being worked on, presumably to tweak the interface for Phones. This doesn't mean that they use different underlying code though. 
  • Good one Daniel. Now that all of us windows fans know the distinction, try to get this on to some of the other mobile nations sites. Perhaps add some points on the advantages of such a system. I guess this may appeal to some people on rival platforms too. Be the crusader that we so desperately need.
  • Something nice about the UWP is that the controls are remarkably adaptive. Be it a simple button, a stacked list of items, or more complex things like pivots and wrapping grids, it works as you would expect on every device, without the developer having to do anything. You don't have to check for mouse clicks, or swiping your finger to scroll a list - everything "just works."
  • Another big issue for some apps is the wide range of DPIs that need to be supported, which can go from 96 dpi (the Desktop standard) up to 192 dpi or more. If your app uses raster assets (icons, bitmaps, etc.) in the UI then you need to make several sizes of them so that they're clean at different DPI screens. You don't want to use the built-in scaling for such assets because it looks terrible. This isn't a problem just for UWP, it's also a problem on Win32 with its High DPI support. A 13.3" laptop with a 1920x1080 screen is around 168 dpi. With a 3200x1800 screen like the Lenovo Yoga Pro 2/3 and others, the DPI zooms up to 276 dpi.  
  • "However, it is still at the developer's will where and when to release."   Exactly. And this article pretty much shows well why I think UWP will not save WP or do anything for it. You still need developers to want to put their app on the "WP Store" (let's call that to the Store you access on mobile). And since that requires extra work, as you well explained, the developers will have to be willing to put it in. And that means they'll have to take into consideration WP's marketshare. Which at 1.7% doesn't really appeal to anyone. So developers may well continue to skip WP. On the other hand, precisely because they'll likely keep their focus on Windows PCs (where the marketshare is) they might also skip Windows apps altogether and continue to produce x86 programs and direct consumers to the browser. Let us remember that a developer who sells their software themselves through their site (think, for example, Corel) gets way more revenue than if they were selling that same software through the Windows Store (as they won't have to share any profit with Microsoft AND can get extra cash from the advertisement on their websites).   And there's no point in saying "look, this week we got 3/4/5 apps gone Universal". Because while that's nice in the short term, it remains to be seen: 1 - how well will the app be supported going forward? 2 - how long will the developers support the app? UWP is a great idea in theory. But it still has to prove itself more than that. 
  • You are neglecting to remember Windows phone customers will also have a windows work pc, a windows home pc, a windows tablet even a Xbox. If Microsoft gets any app dev to enter the UWP ecosystem on any of them platforms then the expansion onto the other platforms will be relativity easy if the consumer demand is there, this could work both ways as i,m sure there will be plenty WP apps that don't make it to the other platforms due to lack of demand. So all platforms will pull app devs into the UWP, which can only help Win phone...
  • I'm not neglecting. The thing here is that it's the power of the PC that Microsoft is trying to use to put apps on WP. What they hope is that a developer that codes for a W10 PC will also put the app on the WP store. Yes, WP users will also have Windows PCs. But they are 1.7% of the market. There are more Android/iOS users with Windows PCs than there are WP users. And for an Android/iOS user, it's irrelevant that Windows 10 has an app that is also available on WP because it's not the platform (s)he uses on mobile. And so, for developers, even if they put their apps on Windows 10 PCs and tablets, they might still keep them away from mobile because the effort it would take to adapt the app for mobile - as lower as it could be - would still not be worth it.
  • In the other place called 'the rest of the world' Microsoft has 15% and rising... UWP stops exactly what you are pointing out bar UI tweaks and such the base of the code is already written once you have written it for one platform. That is why they are calling it Universal..
  • He isn't American. But he is right in my opinion. Why code for windows mobile? I see the hope and the possibilities but not the why.
  • Because if you've already developed a desktop app using UWP, then pushing that app to mobile is easy work for any developer that knows what they are doing. There are no more excuses to not develop for Windows "mobile". It's marketshare that you wouldn't have gotten otherwise. I find it humurous that the "app" world somehow requires hundreds of millions of potential users to be viable for some of these developers. That is the most absurd business model I've ever seen. What that tells me more than anything is they really aren't offering anythig of value and are just betting on the statistics of large numbers. "Well, if we have a billion potential users, and some small fraction are dumb enough to download our app, then we can make a bunch of money."
  • Which part of the world is that? According to latest Kantar numbers Windows Phone/Win 10 Mobile has heavily lost marketshare in October and November. In Italy, one of WP strongest markets, it's down from 14% to 9%. Germany is down from 11% to 6%, Spain is down, Japan is down, India is down. So what part of the world are you talking about where Microsoft has 15% smartphone marketshare? And to add to DJBS' point: Even Nadella said that universal apps are not bringing developers to Windows 10 Mobile. That's why he asked for more time and to wait until Holo Lense will be released. Because maybe then developers will chose to develop for Windows again.
  • Quoting figures before the 950 launch are obviously going to be down people are waiting for the new phone...Lets see what happens with the new figures... Why don't you read the posts earlier by the actual developers or the actual  article itself and understand where they are coming from? your devs this, devs that but ignore what any dev has said on this forum obviously because developers no less about what they are going to do than punters do... You know at the end of the day go get a iphone, why waste your time telling people that have bought into windows 10 concept, that it is crap. Jus toodle along to the istore and apple forums and tell them? There has been about 30 universal apps out since i bought my 950(which is the best phone i have ever owned by a country mile) how long will it be before you believe? Never? I can see myself using full version software on my windows phone in a couple of years and people will still be here professing w10 is rubbish because it hasnt got Snapchat...
  • "Quoting figures before the 950 launch are obviously going to be down people are waiting for the new phone..."   No, they are not. Flagship phones have NEVER been what drove Windows Phone marketshare. Just look at all the charts referencing WP devices in use by popularity etc (AdDuplex etc) and you'll see it's the budget WP offers that dominate. The 950 and the 950XL will do ZERO for the WP marketshare. Because only those really into WP will burn 500€-700€ on a WP device with an unfinished OS, crappy performance and very very poor app ecosystem. And those people are already on WP, they're not new users.   As for developers that write on WCentral...yeah, those are *clearly* the ones that bring the users. It's the developers of Instagram, Facebook, Banking apps etc that come and write on WCentral.
  • WP is at 1.7% WORLDWIDE. It's a number for the entire World, not the USA. Also, I'm not American. I'm European. Oops...
  • Great article Danny!
  • So, Universal Apps strategy seems to be working should I say? Because looking at the recent updates and apps, I'm excited. :)
    I don't remember companies and apps adapting to wp 8.1 that fast..
  • It depends on the app. If it were a basic clock app with no configurable settings, you could probably write once and publish to all. It's technically true, just not advised...
  • Is it possible to create a W10M app that runs in continuum mode, but won't run in phone mode? Is that even a target option? Obviously the opposite is true, hence why they're greyed out in the continuum start menu... I can't think of good usage scenario for this at the moment, but it's just a thought that crossed my mind.
  • Nicely written Dan, thank you!
  • Now some of us don't have to type illogical things to convince a user having doubts about "Universal but not everywhere" issue.. Thanks for this simple article Dan.. Even my grand pa can understand... Simply the best ( courtesy: HBO ) :p
  • Thanks for taking the time to explain why universal apps aren't happening as fast as people would like them too. As someone who really doesn't use that many apps, I hope that universal apps take off for those who uses apps more frequently than I.
  • Actually, I think they are coming along quite well. As an example, The Wall Street Journal just released their new Windows 10/Mobile app and it's fantastic. This is the first time they've had an app of any substance on the entire Windows platform. Yes, they've had an app for a while, but it was basically a reused Microsoft News app with WSJ content. Now they have a proper Windows 10/Moblie presence.
  • Because devs are lazy?
  • I get the direction and the reason behind the Universal App.  I think that you can spin things every which way, but they shouldn't be pushing that an app is Universal if really they're saying it shares a bulk of the code base or kernal that can then be used across other devices, but that's not really Universal.  Just call it an app that shares a bulk of it's code with an app that can run on a different device.  A true Universal app in my opionon is one that has ALL of it's coding in place so you can truly have just one app to run everywhere in which case within the coding, the dev is set in modifying conditions to include "view states" that expand and collapse at different resolutions.  Some apps are truly Universal in that sense.  Some are just code made specifically for one type of device that is written in a way such that it would be "fairly easy" to spin off for other devices because a bulk of the coding is set for that.
  • Needs Must... The true Universal app is the goal but as for example Netflix the dev has found it and many will at first to get the app out on all or some of the platforms then work on the code that unifies them rather than have the individual platform apps waiting on the shelf .
  • What you described is exactly what UWP is and is exactly how it works. Universal code with view states.
  • Minecraft for Windows 10 should be universal.
  • I knew that good job though for those who did not.
  • The information is well explained in a simple way. I like that....
  • How can information escape a black hole, but not light? Are we talking information in the way of radio waves?
  • Well, if a developer builds a touch-centric app and excludes pc users, that app won't be available on my windows 10 tablet, which obviously has touch. The apps should be restricted based on required capabilities, not what device it is.
  • As a developers, it is very hard to code on Universal when you were used to Silverlight (Windows Phone 8 type), like List, we use LongListSelector in Windows Phone 8, and it is very easy to implement headers (the alphabet header). When migrating to RunTime (Universal), it use listView, if you want header with jumplist (clicking alphabet will show a grid of alphabet), you have to use SemanticZoom. The problem is that there's no documentation for how to do jumplist on Microsoft Windows/Windows Phone documentation, and I found only few can explain how to use it, but not clearly describe WHY you code like it.
  • Another reason not mentioned in the article is that some developers may want to use a different business model for mobile and desktop/tablet.
  • I wonder if this Daniel Rubino guy is paid by MS, or wishes to be at some point to write so positive stuff for every Microsoft failure out there, making it looks like a success (often subliminally)
  • If it's not universal it's not universal!
  • Not sure a black hole -> windows 10 is the best allegory when trying to promote the platform if you know what I mean.
  • Great write up but can some Devs weigh in on what it would take time wise and if it makes sense to put the app on all of Windows 10's platforms. 
  • Just curious, broadly speaking, how mucher longer does it take to make a, say, phone app from a PC app? 20% more time? Posted via the Windows Central App for Android
  • 'Code once, run anywhere' might mean it's the same code and it could run anywhere but for some reasons it doesn't to developers. However, to customers it means code once and it will run anywhere. If Microsoft was a company which only sold to developers then the 'it's the same code, it's not the same code' debate would matter. Trust me, to customers it doesn't.  No wonder Apple is dominant in the consumer space. 
  • To make this work there has to be Android or iOs app development.
  • could you imagine the outcry if someone saw a usefull Microsoft app in the Apple App Store advertising section, Apple Magazine, or Apple website, and it stated that you need a windows phone and a dock to use it...but it was a genuine Apple sourced.  I coudl jsut see it...   iTunes on your TV WHILE you talk on the phone and get a text and respond to an email ALL without stopping iTunes.....  
  • I really appreciated your article. Can finally speak with "some" intelligence to my iPhone toting nephews and nieces. :) Personally I love my WP10 with Windows Insider previews, glitches and all. My Lumina 1020 is doing a great job of hanging in there. Looking forward to purchasing a 950XL in the new year.
  •     After reading your article, Ive come to the realization that Microsoft really needs A surface phone, but it needs to be 95% flawless out the gate.  In my opinion They should market it with a dule personality Pro running an X86 chip and non pro running an ARM.  If they can find a sweet spot on screen size between the two. The market will flood with Apps.  Then all they have to do is market a cheaper non surface phone that utilizes the same screen size.  That way app developers dont have to screw with making things flow or look correctly.   One of the biggest advantages apple has over microsoft is that they didnt really screw with screen sizes for a long long time.  It made it easier for developers to make cookie cutter apps.  Microsoft on the other hand has a plathoramof windows phones with different screen sizes....    
  •    Thanks for the article. Hopefully, this will clear things up for everybody.
  • One thing that really highlights the common code aspect of UWP apps is Continuum. When you attach that 20"+ monitor and open up a 'universal' app, look at it and look at the same app running on a Surface or desktop. They are the same, and clearly the one on Continuum is running on the phone. So either the mobile developer did a heck of a lot of extra work to make that mobile app look and feel like the desktop version, just to fool us, or he did the work once, and it really is the same code base, just reacting to what it is running on and where.  I get that there is effort to making sure what happens when the 'scaling' kicks in works well, but it is not two different distinct efforts.  Another example is to minimize a Universal app window on a Win 10 laptop down to a phone sized window. Notice how it rearranges itself to look like the phone 'version' of the app. Very clear in mail where the reading pane disappears as you get smaller, and  when selected, an email from the list, replaces the list with the text of the mail, just like on the phone.
  • Microsoft needs alot of time to improve the OS  and apps because most of the people are blaming OS and APPS are not stable.