iOS UIView Animation CATransform3DMakeRotation confusion

问题

I have a UIView that I am trying to animate flipping down, while having its axis at the bottom of the view. E.g.:

To do this, I am trying to use a UIView animation:

[UIView animateWithDuration:3 delay:0 options:UIViewAnimationCurveEaseOut animations:^{

     // Flip Down
     top3.layer.anchorPoint = CGPointMake(0.5, 1.0);
     top3.layer.transform = CATransform3DMakeRotation(M_PI, 1, 0, 0);

 } completion:^(BOOL finished) {

     // Reset?
     //top3.transform = CGAffineTransformMakeScale(1, 1);

 }];

Right now it isn't working how I want, it seems like the view is animating AWAY from the user rather then toward. It does't seem to give a 3D effect that makes it look closer to the user when rotating down, as shown in my image. I am positive that this is because of my lack of understanding how to use CATransform3DMakeRotation.

Questions:

How can I make the view appear closer to the user as it drops? Such as skewing it as in my image example?
When I set my anchorPoint it shifts my view down, how can I prevent this and still set my anchorPoint?
~~With UIView animation, can I use easing settings?~~ Used UIViewAnimationCurveEaseOut in options.
Can I use gravity settings?

回答1:

It’s not completely clear from your question, but it sounds like you’re not seeing a perspective distortion during the animation—the view’s staying rectangular as it rotates, right? For a CALayer to display with perspective, its transform needs to have the m34 element set, as described here.
To compensate for the anchorPoint moving your view’s layer, you need to change the view’s original position.
Yes. There are several animation options in addition to the one you’re using, and you can combine them like this (for example): UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionCurveEaseInOut | UIViewAnimationOptionAllowUserInteraction.
Core Animation doesn’t really have any concept of physics. Depending on the effect you’re going for, you can achieve it by chaining multiple animations together with particular easing settings—for instance, a falling object that hits a solid surface would use an “ease in” animation on its way down, then an “ease out” if it then bounced back up.

来源：https://stackoverflow.com/questions/8494184/ios-uiview-animation-catransform3dmakerotation-confusion

标签

ios

uiview

core-animation

uiviewanimation