Xcode 11 - Disable resize mode in catalyst swift

You can call this in your application:didFinishLaunchingWithOptions method:

    UIApplication.shared.connectedScenes.compactMap { $0 as? UIWindowScene }.forEach { windowScene in
        windowScene.sizeRestrictions?.minimumSize = CGSize(width: 480, height: 640)
        windowScene.sizeRestrictions?.maximumSize = CGSize(width: 480, height: 640)
    }

Beta 5 added a sizeRestrictions property to UIWindowScene.

If you set sizeRestrictions.maximumSize and sizeRestrictions.minimumSize to the same value, the window will not be resizable:

windowScene.sizeRestrictions?.minimumSize = CGSize(width: 640, height: 480)
windowScene.sizeRestrictions?.maximumSize = CGSize(width: 640, height: 480)

The easiest place to add this code is probably scene(_:willConnectTo:options:) in your scene delegate. The scene object passed in is a UIWindowScene, so just cast it and then set sizeRestrictions.

Note: sizeRestrictions are only available in iOS 10.15 Beta 5. This code will crash in older betas.