View-controller methods for resizing view when keyboard is shown/hidden (from Apple's UICatalog sample)

keyboardShowHide.m

- (void)keyboardWillShow:(NSNotification *)aNotification
{
    // the keyboard is showing so resize the table's height
    CGRect keyboardRect = [[[aNotification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    NSTimeInterval animationDuration = [[[aNotification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    CGRect frame = self.view.frame;
    frame.size.height -= keyboardRect.size.height;
    [UIView beginAnimations:@"ResizeForKeyboard" context:nil];
    [UIView setAnimationDuration:animationDuration];
    self.view.frame = frame;
    [UIView commitAnimations];
}

- (void)keyboardWillHide:(NSNotification *)aNotification
{
    // the keyboard is hiding reset the table's height
    CGRect keyboardRect = [[[aNotification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    NSTimeInterval animationDuration = [[[aNotification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    CGRect frame = self.view.frame;
    frame.size.height += keyboardRect.size.height;
    [UIView beginAnimations:@"ResizeForKeyboard" context:nil];
    [UIView setAnimationDuration:animationDuration];
    self.view.frame = frame;
    [UIView commitAnimations];
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
	
    // listen for keyboard hide/show notifications so we can properly adjust the table's height
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillShow:)
                                                 name:UIKeyboardWillShowNotification
                                               object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHide:)
                                                 name:UIKeyboardWillHideNotification
                                               object:nil];    
}

- (void)viewDidDisappear:(BOOL)animated
{
    [super viewDidDisappear:animated];
	
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:UIKeyboardWillShowNotification
                                                  object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                                    name:UIKeyboardWillHideNotification
                                                  object:nil];
}