Turns out, Windows 10 isn’t going to run Android apps, as rumors predicted ahead of Microsoft’s Build developer conference on Wednesday. But the company promises that it will be easy for developers to port existing Android and iOS apps to work on Windows.

It’s part of Microsoft’s much larger play to turn Windows into a developer ecosystem that can go toe-to-toe with Apple and Google. Windows 10, scheduled for launch this summer, is Microsoft’s first attempt at an operating system that will run on a wide variety of devices—from phones and tablets through PCs, as well as its forthcoming HoloLens holographic computer.

A unified Windows 10 potentially offers developers a single big market for their apps. Microsoft executive Terry Myerson, in fact, promised that within “two to three years” following the launch of Windows 10, the operating system will be running on a billion devices worldwide.

How To Get Apps

Key to that vision, though, is getting developers to write more “universal” Windows apps that will run across all those different devices. Windows has long trailed both Google and Apple in terms of the number of apps it offers.

To get from here to there, then, presents a challenge. It’s one Microsoft plans to meet in part by convincing developers to reconfigure, or “port,” Android and iOS apps to the Windows universal-apps platform.

Porting can be a tremendous pain for developers. At worst, it means rewriting an application from scratch in a new language, using new code libraries and APIs, in order to make it work on a different platform.

Reuse, Recycle and Reduce

Microsoft’s answer to this problem is to let developers reuse code from their existing apps in Windows. In particular, Windows 10 will support Java and C++ code used in Android apps. And Microsoft’s development suite, Visual Studio, will also be able to work with Objective C, the language traditionally used to code apps for iPhones and iPads.

This doesn’t, of course, mean that Android and iOS apps will work on Windows out of the box. Developers will still need to tailor their apps for the Windows environment. Presumably Windows will offer new APIs (see our API explainer) to replace ones that are native to iOS or Android, and devs will still need to rewrite their apps to use the new APIs.

Such porting efforts can be fraught with unexpected difficulties, no matter how simple companies claim they’ll be. Amazon’s App Store, for instance, requires developers to do some reworking of their Android apps before it will accept them (mostly to ensure they use Amazon APIs instead of Google’s).

Even though you’d think Android is Android, that hurdle alone has proven a major impediment for many app developers. The Amazon store had only 293,000 apps as of January, compared to an estimated 1.4 million in the Google Play Store.

There’s one more wrinkle, too; Microsoft said nothing about Swift, the new Apple language for iOS app development that’s quickly supplanting Objective C.

Lead image courtesy of Microsoft