问“红色警报”动画效果与石英2D或CALayer动画？

EN

self.uiView1.backgroundColor = [UIColor redColor];

CABasicAnimation* selectionAnimation1 = [CABasicAnimation 
                                        animationWithKeyPath:@"opacity"];

selectionAnimation1.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];

selectionAnimation1.fromValue = [NSNumber numberWithFloat:0.0];
selectionAnimation1.toValue = [NSNumber numberWithFloat:1.0];

selectionAnimation1.duration = 0.10;
selectionAnimation1.repeatCount = 20;

[self.uiView1.layer addAnimation:selectionAnimation1
                       forKey:@"opacity"];


self.uiView2.backgroundColor = [UIColor blackColor];

CABasicAnimation* selectionAnimation2 = [CABasicAnimation 
                                        animationWithKeyPath:@"opacity"];

selectionAnimation2.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];

selectionAnimation2.fromValue = [NSNumber numberWithFloat:1.0];
selectionAnimation2.toValue = [NSNumber numberWithFloat:0.0];

selectionAnimation2.duration = 0.10;
selectionAnimation2.repeatCount = 20;

[self.uiView2.layer addAnimation:selectionAnimation2
                          forKey:@"opacity"];