iOS 13 Crash with SwipeKeyboard and textfield:shouldChangeCharactersIn: - ios

Question

In iOS 13, when implementing shouldChangeCharactersIn via the UITextfieldDelegate, the application crashes when using the swiping keyboard.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if let text = textField.text as NSString? {
let txtAfterUpdate = text.replacingCharacters(in: range, with: string)
textField.text = txtAfterUpdate
}
return false
}
Is this an Apple bug?

Answer 1

I was able to reproduce this - if you mutate the state of the text on a UITextField during swipe entry - and only during swipe entry, it'll attempt to reinsert the swiped content (even if you return false), which retriggers your delegate event, which kicks off the recursive cycle.
It's a bit of a hack but you could catch it with something like
private var lastEntry: String?
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if string.count > 1 && string == lastEntry { // implies we're swiping or pasting
print("Caught unwanted recursion")
return
}
lastEntry = string
if let text = textField.text as NSString? {
let txtAfterUpdate = text.replacingCharacters(in: range, with: string)
textField.text = txtAfterUpdate
}
return false
}
It'll stop users from pasting/swiping the same thing twice in a row, but at least it'll let them swipe while Apple fixes their problem.

Answer 2

I used UIPasteboard to identify when the user is pasting and then leave the text as the user entered using the swipe like this:
public func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
//check if the user used swipe keyboard
if string.count > 1 && string != UIPasteboard.general.string ?? "" {
return true
}
//do the text treatment
return false
}
I also realized that the TextField only accepts static strings when using swipe keyboard.
Hope it Helps.

Answer 3

Before setting text you can reset delegate and after set it to self again.
But this solution has one problem if textfield is empty - text will be doubled.
Му code example:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let currentText: String = textField.text ?? ""
if #available(iOS 13, *) {
textField.delegate = nil
let resultText = editedText
textField.text = resultText
if currentText.isEmpty, textField.text != resultText {
textField.text = resultText
}
textField.delegate = self
} else {
textField.text = input.result
}
return false
}