CAKeyframeAnimation－关键帧动画

//关键帧动画 CAKeyframeAnimation- (void)keyAnimation{    CALayer *layer =[CALayer layer];    layer.bounds = CGRectMake(0, 0, 100, 100);    layer.position = CGPointMake(100,100);    layer.backgroundColor = [UIColor yellowColor].CGColor;    [self.view.layer addSublayer:layer];    CAKeyframeAnimation *anim = [CAKeyframeAnimation animation];    anim.keyPath = @"position";    anim.removedOnCompletion = NO;    anim.fillMode = kCAFillModeForwards;    anim.duration = 2.0;    CGMutablePathRef path = CGPathCreateMutable();    CGPathAddEllipseInRect(path, NULL, CGRectMake(100, 100, 200, 200));    anim.path = path;    CGPathRelease(path);    // 设置动画的执行节奏    // kCAMediaTimingFunctionEaseInEaseOut : 一开始比较慢, 中间会加速,  临近结束的时候, 会变慢    anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];    anim.delegate = self;    [layer addAnimation:anim forKey:nil];}