UITextField does not receive text changes

Question

we have a simple UITextField which lies on a second UIWindow. Touching it will correctly make it the first responder and a keyboard will be shown. However, no touched key, but the backspace, fires the textField:shouldChangeCharactersInRange:replacementString:. Every other UITextFieldDelegate method is being correctly fired. The textfield is created in an Interface Builder and it is not subclassed. Nothing seem to be stealing a first responder.

The bug occurs only on an iPhone 3GS, iOS 6.1.6.

Answer 1

Apparently, only the key window does get the changes from a first responder. It is as simple as to call makeKeyWindow on the appropriate window.

From the documentation:

Makes the receiver the main window.