calayer-contents-on-ios14.md

CALayer's contents property on iOS 14

Prior to iOS14, the contents is initialized right after you set image for the UIImageView. So you can use the contents property latter to do whatever you want, for example taking snapshot.

But start from iOS 14, the contents is not initialized until the UIImageView is added to the view's hierarchy or after the snapshotView(afterScreenUpdates: true) is called on the UIImageView.

So what do you do when you need to get the contents before the view is added to the view's hierarchy?

CALayer's displayIfNeeded comes to rescue

You can force iOS to inititate the contents before you want to use it.

if myImageView.contents == nil {
  myImageView.setNeedsDisplay()
  myImageView.displayIfNeeded()
}