Get the current text in the UITextField when UITextField has been changed

DetectTextFieldChanged.m

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    
    NSString *currentStr;
    if ((range.length == 0 && string.length > 0) || (range.length > 0 && string.length > 0)) {
        // add the characters to textfield
        NSString *firstHalfStr = [textField.text substringToIndex:range.location];
        NSString *lastHalfStr = [textField.text substringFromIndex:(range.location + range.length)];
        currentStr = [NSString stringWithFormat:@"%@%@%@",firstHalfStr,string,lastHalfStr];
    }else{
        // delete characters from textfield
        NSString *firstHalfStr = [textField.text substringWithRange:NSMakeRange(0,range.location)];
        NSString *lastHalfStr = [textField.text substringFromIndex:(range.location+range.length)];
        currentStr = [NSString stringWithFormat:@"%@%@",firstHalfStr,lastHalfStr];
    }
    return YES;
}