Between common and uncommon

- (IBAction)toggleFlay:(id)sender

{

    if ([helicopterImageView isAnimating]){

        [helicopterImageView stopAnimating];

    } else {

        [helicopterImageView startAnimating];

    }

}

- (IBAction)moveThroughPath:(id)sender

{

    birdImageView.hidden = NO;

    //패쓰 만들기

    CGMutablePathRef aniPath = CGPathCreateMutable();

    CGPoint currCenter = helicopterImageView.center;

    CGAffineTransform xform = CGAffineTransformIdentity;

    CGPathMoveToPoint(aniPath, &xform, currCenter.x, currCenter.y);

    CGPathAddCurveToPoint(aniPath, &xform, -200, currCenter.y, 520, 400, 160, 400);

    //애니메이션 만들기

    CAKeyframeAnimation *keyAni = [CAKeyframeAnimation animation];

    keyAni.duration = 4.0;

    keyAni.path = aniPath;

    keyAni.rotationMode = kCAAnimationRotateAutoReverse;

    //레이어에 애니메이션을 더한다

    [NSTimer scheduledTimerWithTimeInterval:0.1

   target:self

 selector:@selector(collisionCheck:) userInfo:nil repeats:YES];

    [helicopterImageView.layer addAnimation:keyAni forKey:@"position"];

}

- (void)collisionCheck:(NSTimer *)timer

{

    CALayer *presentationLayer = helicopterImageView.layer.presentationLayer;

    CGRect presentationRect = presentationLayer.frame;

    CGRect birdRect = birdImageView.frame;

    if (CGRectIntersectsRect(presentationRect, birdRect)){

        NSLog(@"Collision");

        birdImageView.hidden = YES;

        [timer invalidate];

        timer = nil;

    }

}