gistfile1.m

- (void)viewDidLoad
      {
          [super viewDidLoad];
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(keyboardWillShown:)
                                                     name:UIKeyboardWillShowNotification object:nil];
        
        
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(keyboardWillBeHidden:)
                                                     name:UIKeyboardWillHideNotification object:nil];
    }
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{

    if ([self respondsToSelector:@selector(preferredContentSize)]) {
        self.preferredContentSize = CGSizeMake(320, 480);
    }
}

- (void)keyboardWillShown:(NSNotification*)aNotification
{
    if (![self isPortraitOrientation] && [self respondsToSelector:@selector(preferredContentSize)]) {
        self.preferredContentSize = CGSizeMake(320, 200);
    }
}
- (BOOL) isPortraitOrientation {
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
    if ( UIDeviceOrientationUnknown == orientation || UIDeviceOrientationFaceUp == orientation || UIDeviceOrientationFaceDown == orientation ) {
        orientation = (UIDeviceOrientation)[[UIApplication sharedApplication] statusBarOrientation];
    }
    return UIDeviceOrientationIsPortrait(orientation);
}