CAShapeLayer 动画

CAShapeLayer *circle = [CAShapeLayer layer];

[circle setPath:[[UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 150, 150)] CGPath]];

[circle setStrokeColor:[[UIColor blueColor] CGColor]];

[circle setFillColor:[[UIColor clearColor] CGColor]];

[[self.view layer] addSublayer:circle];

CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];

pathAnimation.duration = 1.5f;

pathAnimation.fromValue = [NSNumber numberWithFloat:0.0f];

pathAnimation.toValue = [NSNumber numberWithFloat:1.0f];

pathAnimation.repeatCount = 10;

pathAnimation.autoreverses = YES;

[circle addAnimation:pathAnimation
              forKey:@"strokeEnd"];

http://i.stack.imgur.com/jzSkM.gif