That revelation set off quite a storm on Twitter and in comments on blogs (including mine). How are developers supposed to be ready with apps that take advantage of Windows 8.1's new features and programming interfaces if they can't get access to the RTM bits ahead of the October 18 Windows 8.1 launch?
In the case of Windows Phone 8, Microsoft officials said they were holding back the SDK out of fear they'd reveal new features that they didn't want known until launch. (There were no major new features for Windows Phone 8 revealed during the launch that hadn't leaked previously.) In the Windows 8.1 case, secrecy doesn't seem to be the reason; instead, Microsoft is still updating the RTM code -- and plans to do so right up until just before launch.
Between now and October 18, the Softies reiterated, developers should code against the Windows 8.1 customer preview bits that were released in late June, using the Visual Studio 2013 preview, which also was released to testers in late June. By doing so, developers can begin updating their apps to take advantage of Windows 8.1 features including faster app startup times, improved animation rendering, additional tile sizes and templates, the new Bing-centric search experience, new controls and more, Microsoft officials say.
On October 18, once the Windows Store opens, developers will be able to "onboard" new apps or an 8.1 version of their existing Windows 8 apps using the same app ID. That will allow developers to have their 8 and 8.1 apps share ratings and reviews, as well as allow users to automatically get the 8.1 verion of an app when they update. It also will allow developers to update both their Windows 8 and 8.1 apps if they choose.
Microsoft officials said there will be more guidance coming on the Windows App Builder blog "(a)s we approach the general availability of Windows 8.1 and of Visual Studio 2013." (That wording makes me think VS 2013 might not be generally available until October 18 or so. But no one from Microsoft is saying for now.) The other place to check for information on getting apps ready for publishing to the Windows Store in 8.1 is the Windows Dev Center, the Softies said.
I'd like to hear from Windows developers who have built Windows 8 apps about what you've found re: how your app works or doesn't on Windows 8.1 customer preview. And anyone writing apps that take advantage of Windows 8.1's new features: Anything you're concerned as Microsoft marches toward launch?