1.使用 NSTimer 来实现

 

[NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(setNeedsDisplay) userInfo:nil repeats:YES];

 

 

 

2.使用 CADisplayLink 来实现

CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(setNeedsDisplay)]; [link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];