There are a ton of guides out there for updating your app(s) to support the iPhone X.
If you create your view programmatically, you can use iOS 11’s safeAreaLayoutGuide. If your app targets iOS 10 or below, you can use the availability condition, #available().
With the Storyboard, one thing I appreciate from Apple is making the safe area layout guide backwards deployable.
Apple told us in WWDC 2017 Session 412 that Storyboards using safe areas are backwards deployable. This means you can switch to using the safe area layout guide in Interface Builder even if you still target iOS 10 and older.
I don’t always use the storyboard for my layouts, but for apps that I need to update, this backwards deployability helps a lot.