Did you migrate your app from an earlier version of Xcode? If so then Xcode is now making an assumption about your screen size and you need a way of indicating the actual screen size at run time.
There are two ways:
a) If you use a launch screen.
You are missing a LaunchScreen.storyboard file.
Create a Launch Screen object from the New File... dialog
b) If you don’t use a launch screen.
Go to your Target’s settings and choose General, then App Icons and Launch Images.
Now set “Launch Screen File” to your “main.storyboard” (or another storyboard if appropriate)