定时器

1.

CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(setNeedsDisplay)];

    [link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];

2.

[NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(setNeedsDisplay) userInfo:nil repeats:YES];