iOS 定时任务

double delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC); 
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){ 
    //执行事件
});

NSTimeInterval period = 1.0; //设置时间间隔

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0), period * NSEC_PER_SEC, 0); //每秒执行

dispatch_source_set_event_handler(_timer, ^{
    //在这里执行事件
});

dispatch_resume(_timer);

dispatch_cancel(_timer);
_timer = nil;

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(action:) userInfo:nil repeats: YES];

NSTimer *timer = [NSTimer timerWithTimeInterval:5 target:self selector:@selector(timerAction) userInfo:nil repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];

[timer invalidate];

self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(handleDisplayLink:)];    
[self.displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

[self.displayLink invalidate];  
self.displayLink = nil;