GCD队列

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
[self syncConcurrent];
}

• 同步函数＋主队列 没有开启新的线程 串行执行任务 会造成线程阻塞 你等我来我等你结果就耗着了

 -(void)syncMain{
    //1、获得主队列
dispatch_queue_t queue = dispatch_get_main_queue();
NSLog(@"%s",__func__);
    //2、将任务加进队列
dispatch_sync(queue, ^{
    NSLog(@"1----%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
    NSLog(@"2----%@",[NSThread currentThread]);
});
/*2016-07-27 22:03:18.257 GCD[1474:205778] -[ViewController syncMain]*/
}

• 异部函数＋主队列 只在主线程中执行任务，没有开启新线程 串行执行任务

-(void)asyncMain{
//1、获得主队列
dispatch_queue_t queue = dispatch_get_main_queue();
//2、将任务添加进队列
dispatch_async(queue, ^{
    NSLog(@"1----%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
    NSLog(@"2----%@",[NSThread currentThread]);
});
dispatch_async(queue, ^{
    NSLog(@"3----%@",[NSThread currentThread]);
});
/*
 2016-07-27 22:01:12.524 GCD[1461:204697] 1----{number = 1, name = main}
 2016-07-27 22:01:12.525 GCD[1461:204697] 2----{number = 1, name = main}
 2016-07-27 22:01:12.526 GCD[1461:204697] 3----{number = 1, name = main}
 */
}

• 同步函数＋串行队列 开启新的线程 串行执行任务

-(void)syncSerial{
//1、获得串行队列
dispatch_queue_t queue = dispatch_queue_create("com.mudy.queue", DISPATCH_QUEUE_SERIAL);
//2、将任务添加到队列中
dispatch_sync(queue, ^{
     NSLog(@"1----%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
    NSLog(@"2----%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
    NSLog(@"3----%@",[NSThread currentThread]);
});
/*
 2016-07-27 22:09:31.890 GCD[1509:209789] 1----{number = 1, name = main}
 2016-07-27 22:09:31.891 GCD[1509:209789] 2----{number = 1, name = main}
 2016-07-27 22:09:31.892 GCD[1509:209789] 3----{number = 1, name = main}
 */
}

• 异部函数 ＋ 串行队列 :会开启新的线程，但是任务是串行的，执行完一个任务，在执行下一个任务

  -(void)asyncSerial{
  
  dispatch_queue_t queue = dispatch_queue_create("com.mudy.queue", DISPATCH_QUEUE_SERIAL);
  dispatch_async(queue, ^{
    NSLog(@"1----%@",[NSThread currentThread]);
  });
  dispatch_async(queue, ^{
    NSLog(@"2----%@",[NSThread currentThread]);
  });
  dispatch_async(queue, ^{
    NSLog(@"3----%@",[NSThread currentThread]);
  });
  /*
   2016-07-27 22:11:47.582 GCD[1531:211558] 1----{number = 2, name = (null)}
   2016-07-27 22:11:47.584 GCD[1531:211558] 2----{number = 2, name = (null)}
   2016-07-27 22:11:47.585 GCD[1531:211558] 3----{number = 2, name = (null)}
   */
  }
  

• 同步函数 ＋ 并行队列 :不会开启新的线程，串行执行任务

-(void)syncConcurrent{
dispatch_queue_t queue = dispatch_queue_create("com.mudy.queue", DISPATCH_QUEUE_CONCURRENT);
dispatch_sync(queue, ^{
    NSLog(@"1-------%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
    NSLog(@"2-------%@",[NSThread currentThread]);
});
dispatch_sync(queue, ^{
    NSLog(@"3-------%@",[NSThread currentThread]);
});
/*
 2016-07-27 22:20:11.875 GCD[1560:215430] 1-------{number = 1, name = main}
 2016-07-27 22:20:11.877 GCD[1560:215430] 2-------{number = 1, name = main}
 2016-07-27 22:20:11.878 GCD[1560:215430] 3-------{number = 1, name = main}
 */
}

• 异步函数 ＋ 并行队列：有开启新的线程，并发执行任务

  -(void)asyncConcurrent{
  dispatch_queue_t queue = dispatch_queue_create("com.mudy.queue", DISPATCH_QUEUE_CONCURRENT);
  dispatch_async(queue, ^{
    NSLog(@"1-------%@",[NSThread currentThread]);
  });
  dispatch_async(queue, ^{
    NSLog(@"2-------%@",[NSThread currentThread]);
  });
  dispatch_async(queue, ^{
    NSLog(@"3-------%@",[NSThread currentThread]);
  });
  /*
   2016-07-27 22:17:14.859 GCD[1548:213931] 1-------{number = 5, name = (null)}
   2016-07-27 22:17:14.860 GCD[1548:213866] 2-------{number = 4, name = (null)}
   2016-07-27 22:17:14.860 GCD[1548:213860] 3-------{number = 2, name = (null)}
   */
  }
  

	并发队列	手动创建的串行队列	主队列
同步	没有开启新线程 串行执行任务	没有开启新线程 串行执行任务	没有开启新线程 串行执行任务
异步	有开启新线程 并发执行任务	有开启新线程 串行执行任务	没有开启新线程 串行执行任务