UIImageView to display fullscreen by tapping using animation.

  @interface viewController : UIViewController <UIGestureRecognizerDelegate>{
    UITapGestureRecognizer *tap;
    BOOL isFullScreen;
    CGRect prevFrame;
}

- (void)viewDidLoad {

    [super viewDidLoad];

isFullScreen = false;
tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(imgToFullScreen)];
tap.delegate = self;
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;
{
    BOOL shouldReceiveTouch = YES;

    if (gestureRecognizer == tap) {
        shouldReceiveTouch = (touch.view == yourImageView);
    }
    return shouldReceiveTouch;
}

-(void)imgToFullScreen{
    if (!isFullScreen) {
        [UIView animateWithDuration:0.5 delay:0 options:0 animations:^{
            //save previous frame
            prevFrame = yourImageView.frame;
            [yourImageView setFrame:[[UIScreen mainScreen] bounds]];
        }completion:^(BOOL finished){
            isFullScreen = true;
        }];
        return;
    } else {
        [UIView animateWithDuration:0.5 delay:0 options:0 animations:^{
            [yourImageView setFrame:prevFrame];
        }completion:^(BOOL finished){
            isFullScreen = false;
        }];
        return;
    }
}