I am working on the iPhone application. I have four textfields in one of the view. In these four textfield I have one textfield in which there will be use of numberpad keyboard. But on numberpad keyboard there is no return key. So I have added "Done"button programmatically by using following code.
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
    [[NSNotificationCenter defaultCenter] addObserver:self                  
            selector:@selector(keyboardDidShow:) 
                                                 name:UIKeyboardDidShowNotification object:nil];        
} else {
    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(keyboardWillShow:) 
                                                 name:UIKeyboardWillShowNotification object:nil];
}
   - (void)addButtonToKeyboard {
// create custom button
UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeCustom];
doneButton.frame = CGRectMake(0, 163, 106, 53);
doneButton.adjustsImageWhenHighlighted = NO;
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.0) {
    [doneButton setImage:[UIImage imageNamed:@"DoneUp3.png"] forState:UIControlStateNormal];
    [doneButton setImage:[UIImage imageNamed:@"DoneDown3.png"] forState:UIControlStateHighlighted];
} else {        
    [doneButton setImage:[UIImage imageNamed:@"DoneUp.png"] forState:UIControlStateNormal];
    [doneButton setImage:[UIImage imageNamed:@"DoneDown.png"] forState:UIControlStateHighlighted];
}
[doneButton addTarget:self action:@selector(doneButton:) forControlEvents:UIControlEventTouchUpInside];
// locate keyboard view
UIWindow* tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];
UIView* keyboard;
for(int i=0; i<[tempWindow.subviews count]; i++) {
    keyboard = [tempWindow.subviews objectAtIndex:i];
    // keyboard found, add the button
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
        if([[keyboard description] hasPrefix:@"<UIPeripheralHost"] == YES)
                               [keyboard addSubview:doneButton];                
    } else {
        if([[keyboard description] hasPrefix:@"<UIKeyboard"] == YES)
                   [keyboard addSubview:doneButton];
        }
     }
    }
     - (void)keyboardWillShow:(NSNotification *)note {
// if clause is just an additional precaution, you could also dismiss it
if ([[[UIDevice currentDevice] systemVersion] floatValue] < 3.2) {
        [self addButtonToKeyboard];
}
  }
       - (void)keyboardDidShow:(NSNotification *)note {
// if clause is just an additional precaution, you could also dismiss it
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2) {
        [self addButtonToKeyboard];
      }
   }
- (void)doneButton:(id)sender {
    NSLog(@"doneButton");
    NSLog(@"Input: %@", contactno.text);
    [contactno resignFirstResponder];
     }
It is fine for this particular textfield. But this button is also get add for the rest of the textfields. How could unhide this button for other textfields. 
                                
thanks alot in advance.