Delegate methods in child class sometimes not called with Swift 5 compiler

Question

EDIT: As sunshinejr pointed out here, this has been fixed and will be released together with the next Xcode/Swift version.

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I\'ve seen a lot of

Answer 1

Since all of UIScrollViewDelegate methods are optionals you will never see an error from compiler if it thinks that you didn't implement them, most probably what is happening is that Apple changed method signature in Swift 5 (again) and for some reason the migration tool didn't work.
Check the methods names along with UIScrollViewDelegate updated to USwift 5 documentation, you will see that probably your methods names are different, simply correct them and everything should work again.