UIView的动画视角可以从底部向上/向下翻转

Question

我有一个观点，我想在这里翻看这个例子。

我目前的解决方案：

[UIView animateWithDuration:duration
                 animations:^{
                     [someView.layer setAffineTransform:CGAffineTransformMakeScale(1, 0)];
                 }];

此解决方案的问题在于顶边向下移动，而底边向上移动。我希望顶边保持不变，底边向上/向外移动，如图所示。

编辑：就像那些猫门，哈哈。你可以用顶部的铰链将光盘/方形表面推离你。

EDIT2：解决方案。

CGFloat someViewHeight = self.someView.frame.size.height;

CATransform3D baseTransform = CATransform3DIdentity;
baseTransform.m34 = - 1.0 / 200.0;
self.someView.layer.zPosition = self.view.frame.size.height * 0.5;
self.someView.layer.transform = baseTransform;

CATransform3D rotation = CATransform3DMakeRotation(- M_PI_2, 1.0, 0.0, 0.0);
CATransform3D firstTranslation = CATransform3DMakeTranslation(0.0, someViewHeight * 0.5, 0.0);
CATransform3D secondTranslation = CATransform3DMakeTranslation(0.0, - someViewHeight * 0.5, 0.0);

self.someView.layer.transform = CATransform3DConcat(CATransform3DConcat(firstTranslation, CATransform3DConcat(rotation, secondTranslation)), baseTransform);

花了一段时间，直到我发现[UIView animateWithDuration:]会为视角或其他东西设置动画，所以动画会缩小视图并做一些我无法解释的奇怪的东西。所以我现在为自己设置动画，只是改变每次的角度。

Answer 1

你的意思是这样的：

    [UIView animateWithDuration:3.0 animations:^{
        [someView.layer setAffineTransform:
         CGAffineTransformConcat(CGAffineTransformMakeScale(1.0f, .0001f), CGAffineTransformMakeTranslation(.0f, someView.frame.size.height*-.5f))];
    }];

这只是解决您所描述的问题，要在图片上显示结果，您需要进行3D转换。

要进行3D转换，事情变得非常棘手：

    CGFloat viewHeight = someView.frame.size.height; //needed later as this value will change because of transformation applied
    CATransform3D baseTransform = CATransform3DMakeTranslation(.0f, .0f, viewHeight*.5f); //put it towards user for rotation radius
    baseTransform.m34 = -1.0/200.0; //this will make the perspective effect
    someView.layer.zPosition = view.frame.size.height*.5f; //needed so the view isn't clipped
    someView.layer.transform = baseTransform; //set starting transform (no visual effect here)

    [UIView animateWithDuration:6.6 animations:^{
        someView.layer.transform = CATransform3DConcat(CATransform3DConcat(CATransform3DMakeRotation(-M_PI_2, 1.0f, .0f, .0f), CATransform3DMakeTranslation(.0f, viewHeight*.5f, .0f)) , baseTransform);
      //or to stay at the same center simply:
      //someView.layer.transform = CATransform3DConcat(CATransform3DMakeRotation(-M_PI_2, 1.0f, .0f, .0f) , baseTransform);
    }];

现在玩一下吧。