iPhone怎么做指定路径的动画

Question

之前做动画一直用这种方法

[UIView beginAnimations:@"animation" context:NULL];
[UIView setAnimationDuration:0.5f];
// 新位置
[UIView commitAnimations];

但是解决不了View需要转向的问题。
我现在需要让这个动画过程中，View有一个抖动的效果，这个实现不了，除非我用延迟，做两次动画，感觉这样很恶心。有没有什么办法是可以指定路径做动画的

Answer 1

用Core Animation，可以指定动画路径。
下面例子实现一个物体下落再弹起的动画

    [CATransaction begin];
    [CATransaction setValue:[NSNumber numberWithFloat:ANIMATION_DURATION] forKey:kCATransactionAnimationDuration];

    CAKeyframeAnimation *positionAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    CGMutablePathRef positionPath = CGPathCreateMutable();
    CGPathMoveToPoint(positionPath, NULL, [theView layer].position.x, [theView layer].position.y);
    CGPathAddQuadCurveToPoint(positionPath, NULL, [theView layer].position.x, - [theView layer].position.y, [theView layer].position.x, [theView layer].position.y);
    CGPathAddQuadCurveToPoint(positionPath, NULL, [theView layer].position.x, - [theView layer].position.y * 1.5, [theView layer].position.x, [theView layer].position.y);
    CGPathAddQuadCurveToPoint(positionPath, NULL, [theView layer].position.x, - [theView layer].position.y * 1.25, [theView layer].position.x, [theView layer].position.y);
    positionAnimation.path = positionPath;
    positionAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
    [[theView layer] addAnimation:positionAnimation forKey:@"positionAnimation"];
    CGPathRelease(positionPath);
    [CATransaction commit];	

当然，在

[CATransaction begin];
...
[CATransaction commit];

代码块中，你可以对一个或多个视图同时添加多个动画效果(如改变其颜色、大小等)，来实现更为复杂的动画

Answer 2

Core Animation。