尝试混合UIKit Dynamics UICollision和core动画来缩放长方体'；界

从我之前的一个问题。

我尝试在一个上面有一个小盒子的盒子上混合动画缩放效果。 这两个盒子都有UICollisionBehavior，我想最终让底部盒子变得更大，足够快，提供一个速度力，让顶部盒子反弹

下面是刻度代码。当视图中的图像仍在缩放时，边界立即设置为其最终目标。我希望边界和图像同时缩放，这样我就可以看到预期的反应发生

- (IBAction)tapBoxThing:(UITapGestureRecognizer *)sender {


    /* Make sure no translation is applied to this image view */
    _boxView.transform = CGAffineTransformIdentity;

    /* Begin the animation */
    [UIView beginAnimations:nil
                    context:NULL];

    /* Make the animation 5 seconds long */
    [UIView setAnimationDuration:5.0f];

    [_gravity removeItem:_boxView];
    [_collision removeItem:_boxView];


    // right here, the box will animate the image in the view to slowly fill in the new bounds.
    // But I want the bounds to animate, its currently instantly scaling to teh final ammount.
    // Core Animation states that frame is not animatable but bounds is.

    CGRect frameZ = _boxView.bounds;
    frameZ.size.height += 60.0f;
    frameZ.size.width += 60.0f;
    _boxView.bounds = frameZ;



   [_gravity addItem:_boxView];
   [_collision addItem:_boxView];


    [UIView commitAnimations];



}