Check out example codes for "how to add undelete texts to textfield in ios". It will help you in understanding the concepts better.
Code Example 1
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if (textField.text.length == 1 && [string isEqualToString:@""]) {//When detect backspace when have one character.
textField.text = @"myText";
}
return YES;
}
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