iOS_延时执行的几种方法

1.最直接的方法performSelector:withObject:afterDelay:

这种方法的缺点：每次要为延时写一个方法

2.使用类别，用BOLCK执行

@implementation NSObject (PerformBlockAfterDelay)

- (void)performBlock:(void (^)(void))block
          afterDelay:(NSTimeInterval)delay
{
    block = [[block copy] autorelease];
    [self performSelector:@selector(fireBlockAfterDelay:)
               withObject:block
               afterDelay:delay];
}

- (void)fireBlockAfterDelay:(void (^)(void))block {
    block();
}

@end

3.使用GCD

void RunBlockAfterDelay(NSTimeInterval delay, void (^block)(void))
{
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC*delay),
      dispatch_get_current_queue(), block);
}

4.可能是不太好的方法，用animation的completion参数

[UIView animateWithDuration:0.0 delay:5.0 options:UIViewAnimationOptionAllowUserInteraction animations:^{
} completion:^(BOOL finished) {
    //do stuff here
}];

5.使用NSOperationQueue，在应用程序的下一个主循环执行：

[[NSOperationQueue mainQueue] addOperationWithBlock:aBlock];

这个和调用

这个和调用performSelector:withObject:afterDelay: of 0.0f等价

转自：IOS_延时执行的几种方法