Handling non-ascii characters in textField:shouldChangeCharactersInRange:replacementString:

Question

I\'m trying to prevent Chinese (or otherwise, all non-ascii characters) from being input into a UITextField. As seen in other posts, I implemented textField:shouldChan

Answer 1

A workaround you can take is to use:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];

then in your function:

- (void)textChanged:(NSNotification *)notification{
  //remove observer
  [[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidChangeNotification object:nil];

  //change your textfield's value here e.g.
  myTextField.text = [MyUtils removeNonAsciiChar:myTextField.text];

  //add observer again
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}

Note however that this is more costly since you will be replacing the entire string everytime, but it should be okay if you're not expecting a very long string.