Dispatch 方法简介

后台执行

dispatch_async(dispatch_get_global_queue(0, 0), ^{ //后台程执行 something; 
}); 

主线程执行

dispatch_async(dispatch_get_main_queue(), ^{// 主线程执行something;
});

 

一次性执行

static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{ // 主要用于单例
});

 

延迟执行

double delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PE R_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){ // code to be executed on the main queue after delay
});

 

创建自定义的线程

dispatch_queue_t myQueue = dispatch_queue_create("com.cnblogs.yybz", NULL); dispatch_async(myQueue, ^{// your code
});

 

设置自定义线程的优先级

 

dispatch_queue_t myQueue = dispatch_queue_create("com.cnblogs.yybz", NULL); 
dispatch_queue_t globalHightQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0); 
dispatch_set_target_queue(myQueue, globalHighQueue);

 

 

组

dispatch_group_async(group, queue, ^{ // code
}); dispatch_group_wait(group, DISPATCH_TIME_FOREVER); //超时参数 
dispatch_group_notify(group, queue, ^{// code
});dispatch_group_enter(group);
dispatch_async(queue, ^{//code
    dispatch_group_leave(group);
});

 

并行同步执行

/**
@parameter iterations 迭代器数量
@parameter queue 提交任务的队列
@parameter (^block)(size_t) 任务Block,size_t 为迭代器下标
**/
dispatch_apply(size_t iterations, dispatch_queue_t queue, void (^block)(size_t));

 

队列挂起与恢复

dispatch_suspend(queue); 
dispatch_resume(myQueue);

 

信号量

dispatch_semaphore_create; //创建一个semaphore
dispatch_semaphore_signal; //发送一个信号
dispatch_semaphore_wait; //等待信号