1.最直接的方法performSelector:withObject:afterDelay: 這種方法的缺點：每次要為延時寫一個方法 2.使用類別，用BOLCK執行

[程式碼]c#/cpp/oc程式碼：

01	@implementation NSObject (PerformBlockAfterDelay)

02

03	- (void)performBlock:(void (^)(void))block

04	afterDelay:(NSTimeInterval)delay

05

{

06	block = [[block copy] autorelease];

07	[self performSelector:@selector(fireBlockAfterDelay:)

08	withObject:block

09	afterDelay:delay];

10

}

11

12	- (void)fireBlockAfterDelay:(void (^)(void))block {

13

block();

14

}

15

16

@end

3.使用GCD

[程式碼]c#/cpp/oc程式碼：

1	void RunBlockAfterDelay(NSTimeInterval delay, void (^block)(void))

2

{

3	dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC*delay),

4	dispatch_get_current_queue(), block);

5

}

4.可能是不太好的方法，用animation的completion引數

[程式碼]c#/cpp/oc程式碼：

1	[UIView animateWithDuration:0.0 delay:5.0 options:UIViewAnimationOptionAllowUserInteraction animations:^{

2	} completion:^(BOOL finished) {

3	//do stuff here

4

}];

5.使用NSOperationQueue，在應用程式的下一個主迴圈執行：

[程式碼]c#/cpp/oc程式碼：

1	[[NSOperationQueue mainQueue] addOperationWithBlock:aBlock];

這個和呼叫performSelector: with afterDelay of 0.0f等價