1 前言

2 代码实例

Demo1：

ZYAppDelegate.m

- (void) printString:(NSString *)paramString{NSLog(@"%@", paramString);
}- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{/*推迟三秒执行printString方法withObject:传的参数*/[self performSelector:@selector(printString:) withObject:@"Grand Central Dispatch" afterDelay:3.0];self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];// Override point for customization after application launch.self.viewController = [[[ZYViewController alloc] initWithNibName:@"ZYViewController" bundle:nil] autorelease];self.window.rootViewController = self.viewController;[self.window makeKeyAndVisible];return YES;
}

运行3秒后控制台结果：

2013-05-10 17:04:52.710 GCDAfterTest[2385:c07] Grand Central Dispatch

Demo2：

ZYAppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{//设置时间为2double delayInSeconds = 2.0;//创建一个调度时间,相对于默认时钟或修改现有的调度时间。dispatch_time_t delayInNanoSeconds =dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);//推迟两纳秒执行dispatch_queue_t concurrentQueue =dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);dispatch_after(delayInNanoSeconds, concurrentQueue, ^(void){NSLog(@"Grand Center Dispatch!");});self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];// Override point for customization after application launch.self.viewController = [[[ZYViewController alloc] initWithNibName:@"ZYViewController" bundle:nil] autorelease];self.window.rootViewController = self.viewController;[self.window makeKeyAndVisible];return YES;
}

运行2秒后控制台结果

2013-05-10 17:06:27.023 GCDAfterTest2[2435:1303] Grand Center Dispatch!

Demo3：

ZYAppDelegate.m

void processSomething(void *paramContext){NSLog(@"Processing...");
}- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{//设置时间double delayInSeconds = 2.0;dispatch_time_t delayInNanoSeconds =dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);//调用C函数processSomethingdispatch_after_f(delayInNanoSeconds, concurrentQueue,NULL,processSomething);self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];// Override point for customization after application launch.self.viewController = [[[ZYViewController alloc] initWithNibName:@"ZYViewController" bundle:nil] autorelease];self.window.rootViewController = self.viewController;[self.window makeKeyAndVisible];return YES;
}

运行2秒后控制台结果

2013-05-10 17:07:27.660 GCDAfterTest3[2476:1303] Processing...

3 结语

以上是所有内容，希望对大家有所帮助。

Demo代码下载：http://download.csdn.net/detail/u010013695/5353603