Making Secure TextField in iOS

Make a secure text field in iOS:

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

{

    const char * _char;

    _char = [string cStringUsingEncoding:NSUTF8StringEncoding];

    int isBackSpace = isBackSpace = strcmp(_char, "\b");

    

    if (isBackSpace == -8)

    {

        NSMutableString *text = [txtPassword.text mutableCopy];

        if (range.length > 0) {

            [text deleteCharactersInRange:range];

        }

        if (range.length == 0 && range.location != 0)

        {

            NSRange backward = NSMakeRange(range.location - 1, 1);

            [text deleteCharactersInRange:backward];

        }

        

        txtPassword.text = text;

        return YES;

        

    }

    

    pass = [pass stringByAppendingString:[NSString stringWithFormat:@"%s",_char]];

    passStar = [passStar stringByAppendingString:@"*"];

    

    txtPassword.text = passStar;

    NSLog(@"text is %@",pass);

    return YES;

}