延迟执行的几种方式

1.GCD 延迟两秒

dispatch_time_t sleepTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC));

dispatch_after(sleepTime, dispatch_get_main_queue(),^{

//延迟执行相关代码

});

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2.performSelector 延迟两秒

[self performSelector:@selector(sleepTime) withObject:nil afterDelay:2.0];

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3.定时器  

[NSTimer scheduledTimerWithTimeInterval:2.0f target:self selector:@selector(sleepTime) userInfo:nil repeats:NO];

repeats: 重复