키보드 높이

    NSDictionary *userInfo = [notification userInfo];

    

    // Get the origin of the keyboard when it's displayed.

    NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];

    

    // Get the top of the keyboard as the y coordinate of its origin in self's view's

    // coordinate system. The bottom of the text view's frame should align with the top

    // of the keyboard's final position.

    //

    CGRect keyboardRect = [aValue CGRectValue];

    keyboardRect = [self.view convertRect:keyboardRect fromView:nil];

    

    CGFloat keyboardTop = keyboardRect.origin.y;