In past I have used shouldChangeCharactersInRange delegate method to intercept the change in characters and make a near guess if it was delete-backspace that was tapped by the user. Guess was based on the nature of replacement character provided in method. If replacement character resembled the special escape character "\b" indicating backspace or empty character when view is already empty.

I felt above direction was a bit hacky. I found that based on response logic I was trying to write was giving me side effect of cursor always jumping to the end of text. For example when I tapped in between the characters of text to set the cursor in position and when I pressed backspace in keypad - I detected the event and did my processing to do some changes to text of UITextField and returned false.

What is the clean solution then?

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The clean solution I found was to create a custom class inheriting UITextField or UITextView; and override deleteBackward to intercept delete event.

class CustomTextField: UITextField {
    override public func deleteBackward() {        
        // detect every backspace. Perform custom operation like calling delegate etc.
        super.deleteBackward()
    }
}

If I wanted to perform delete event check only for empty UITextField or empty UITextView then:

class CustomTextField: UITextField {
    override public func deleteBackward() {
        if text.isEmpty {
             // detect backspace on empty field. Perform custom operation like calling delegate etc.
        }
        super.deleteBackward()
    }
}

The same applies to UITextView too.

Some may be reluctant to go inheritance pattern than something like composition. But this is way cleaner than intercepting in shouldChangeCharactersInRange

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