Optimize your UI.
If you’ve already updated your app for iPhone X, simply build your app with the iOS 12 SDK and test in Simulator, included with Xcode 10, to make sure it looks great on iPhone XS, iPhone XS Max, and iPhone XR. To update your app for these new devices, follow the steps below.
Run and Test in Simulator. Make sure your apps take advantage of the all-screen display by respecting safe areas, supporting adaptive layouts, and more. Read the updated Human Interface Guidelines, download the latest version of Xcode 10, and test your app in Simulator.
Enable full screen native resolution. Your app will run in Full Screen Display Mode on iPhone X, iPhone XS, iPhone XS Max, and iPhone XR if your project’s base SDK is set to iOS 11 or later and you have a Launch Storyboard or iPhone X launch image.
Verify all parts of your app. Make sure that your UI displays correctly and no elements are mispositioned, overlapping, incorrectly scaled, or clipped, especially in landscape mode. If you discover issues, use the safe area guides and layout margins to correctly position UI elements.
If only parts of your app run in Simulator — for example, if it mostly uses UIKit, but has camera integration — you should test as much of your UI as possible by commenting out views that Simulator doesn’t support.
Building Apps for iPhone XS, iPhone XS Max, and iPhone XR