http://blog.csdn.net/wang631106979/article/details/51788622
https://developer.apple.com/documentation/dispatch#//apple_ref/c/func/dispatch_async
- (void)testTargetQueue {
//1.创建目标队列
dispatch_queue_t targetQueue = dispatch_queue_create("test.target.queue", DISPATCH_QUEUE_SERIAL);
//2.创建3个串行队列
dispatch_queue_t queue1 = dispatch_queue_create("test.1", DISPATCH_QUEUE_SERIAL);
dispatch_queue_t queue2 = dispatch_queue_create("test.2", DISPATCH_QUEUE_SERIAL);
dispatch_queue_t queue3 = dispatch_queue_create("test.3", DISPATCH_QUEUE_SERIAL);
//3.将3个串行队列分别添加到目标队列
dispatch_set_target_queue(queue1, targetQueue);
dispatch_set_target_queue(queue2, targetQueue);
dispatch_set_target_queue(queue3, targetQueue);
dispatch_async(queue1, ^{
NSLog(@"1 in");
[NSThread sleepForTimeInterval:3.f];
NSLog(@"1 out");
});
dispatch_async(queue2, ^{
NSLog(@"2 in");
[NSThread sleepForTimeInterval:2.f];
NSLog(@"2 out");
});
dispatch_async(queue3, ^{
NSLog(@"3 in");
[NSThread sleepForTimeInterval:1.f];
NSLog(@"3 out");
});
}
- (void)run{
for (int i = 0; i < 2; ++i) {
NSLog(@"2-----%@", [NSThread currentThread]);
}
}
- (void)dispatchTest1{
dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, globalQueue, ^{
int a = 10;
while (a != 0) {
a --;
}
NSLog(@"111111 %@",[NSThread currentThread]);
});
dispatch_group_async(group, globalQueue, ^{
NSLog(@"2222222 %@",[NSThread currentThread]);
});
dispatch_group_async(group, globalQueue, ^{
NSLog(@"3333333 %@",[NSThread currentThread]);
});
// dispatch_group_notify(group, globalQueue, ^{
// NSLog(@"group Exeture End %@",[NSThread currentThread]);
// });
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
NSLog(@"------------%@",[NSThread currentThread]);
}
- (void)dispatchTest2{
// 我们知道多线程开发最难的就是执行顺序的控制，苹果已经给我们封装好了一些流控制的东西，像dispatch_group，等但是有时候某些场景还是需要我们自己实现对代码执行的控制，毕竟我们不希望自己写的代码自己都不知道执行顺序，dispatch_semaphore就是为了这个目的而存在的，我们可以设置一个cout来控制程序按照我们的意愿来执行。
// 注意：对于这样的阻塞线程的操作，最好不要放在主线程，除非特殊要求。我觉得这应该是我们用多线程开发的共识了。
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_queue_t customSerialQueue = dispatch_queue_create("kongqingyu", DISPATCH_QUEUE_SERIAL);
dispatch_async(globalQueue, ^{
dispatch_sync(customSerialQueue, ^{
[NSThread sleepForTimeInterval:0.1];
NSLog(@"-----------信号即将发送--------");
dispatch_semaphore_signal(semaphore);
});
});
NSLog(@"---------------wait----------");
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
NSLog(@"----------wait end----------");
dispatch_async(globalQueue, ^{
dispatch_sync(customSerialQueue, ^{
[NSThread sleepForTimeInterval:0.1];
NSLog(@"-----------信号即将发送--------");
dispatch_semaphore_signal(semaphore);
});
});
NSLog(@"---------------wait----------");
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
NSLog(@"----------wait end----------");
// dispatch_release(semaphore);
}
-(void)dispatchSignal{
//crate的value表示，最多几个资源可访问
dispatch_semaphore_t semaphore = dispatch_semaphore_create(2);
dispatch_queue_t quene = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
//任务1
dispatch_async(quene, ^{
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
NSLog(@"run task 1");
sleep(1);
NSLog(@"complete task 1");
dispatch_semaphore_signal(semaphore);
});
//任务2
dispatch_async(quene, ^{
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
NSLog(@"run task 2");
sleep(1);
NSLog(@"complete task 2");
dispatch_semaphore_signal(semaphore);
});
//任务3
dispatch_async(quene, ^{
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
NSLog(@"run task 3");
sleep(1);
NSLog(@"complete task 3");
dispatch_semaphore_signal(semaphore);
});
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/**
1、dispatch_queue_t 队列
（1） 队列的创建 dispatch_queue_create()
dispatch_queue_create(const char *_Nullable label,
dispatch_queue_attr_t _Nullable attr); //第一个参数：队列的名称
第二个参数：若是Serial Dispatch Queue 可为NULL／DISPATCH_QUEUE_SERIAL。若为ConCurrent Dispatch Queue，则指定为 DISPATCH_QUEUE_CONCURRENT
通过dispatch_queue_create() 创建的队列使用与默认优先级Global Dispatch Queue 相同执行优先级的线程。
（2）获取系统标准提供的 Dispatch Queue
串行（主线程）： dispatch_get_main_queue()
并行： dispatch_get_global_queue() //有多种执行优先级
2、dispatch_set_target_queue
修改队列的优先级，通过create创建的队列，优先级 与 Global Dispatch Queue的默认优先级 一样。可以通过 dispatch_set_target_queue 方法修改 create 创建队列的优先级。
3、dispatch_after 在 （一段时间）后 将指定的 Block 追加到（指定的）队列中来。
4、dispatch_group
使用Concurrent Dispatch Queue时或者同时使用多个Dispatch Queue 时没在多个处理全部结束时后执行结束处理。
*/