ios 延迟的几种方法

1

dispatch_time_t delayTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0/*延迟执行时间*/ * NSEC_PER_SEC));

dispatch_after(delayTime, dispatch_get_main_queue(), ^{
// to do 
});

2

 [self performSelector:@selector(go:) withObject:nil afterDelay:0.5];

3

 [NSTimer scheduledTimerWithTimeInterval:0.5 repeats:NO block:^(NSTimer * _Nonnull timer) {

    }];