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[操作系统]iOS 多线程GCD的基本使用


《iOS多线程简介》中提到:GCD中有2个核心概念:1、任务(执行什么操作)2、队列(用来存放任务)

那么多线程GCD的基本使用有哪些呢?

可以分以下多种情况:

1、异步函数 + 并发队列

/** * 异步函数 + 并发队列:可以同时开启多条线程 */- (void)asyncConcurrent{  // 1.创建一个并发队列  // dispatch_queue_create(const char *label, dispatch_queue_attr_t attr);  // label : 相当于队列的名字  // dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_CONCURRENT);    // 1.获得全局的并发队列  dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);    // 2.将任务加入队列  dispatch_async(queue, ^{    for (NSInteger i = 0; i<3; i++) {      NSLog(@"this is first %@",[NSThread currentThread]);    }  });  dispatch_async(queue, ^{    for (NSInteger i = 0; i<3; i++) {      NSLog(@"this is second %@",[NSThread currentThread]);    }  });    dispatch_async(queue, ^{    for (NSInteger i = 0; i<3; i++) {      NSLog(@"this is third %@",[NSThread currentThread]);    }  });  }

2、同步函数 + 并发队列

/** * 同步函数 + 并发队列:不会开启新的线程 */- (void)syncConcurrent{  // 1.获得全局的并发队列  dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);    // 2.将任务加入队列  dispatch_sync(queue, ^{    NSLog(@"this is first %@",[NSThread currentThread]);  });  dispatch_sync(queue, ^{    NSLog(@"this is second %@",[NSThread currentThread]);  });  dispatch_sync(queue, ^{    NSLog(@"this is third %@",[NSThread currentThread]);  });  }

3、异步函数 + 串行队列

/** * 异步函数 + 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,再执行下一个任务 */- (void)asyncSerial{  // 1.创建串行队列  dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_SERIAL);  //  dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", NULL);    // 2.将任务加入队列  dispatch_async(queue, ^{    NSLog(@"this is first %@",[NSThread currentThread]);  });  dispatch_async(queue, ^{    NSLog(@"this is second %@",[NSThread currentThread]);  });  dispatch_async(queue, ^{    NSLog(@"this is third %@",[NSThread currentThread]);  });}

4、同步函数 + 串行队列

/** * 同步函数 + 串行队列:不会开启新的线程,在当前线程执行任务。任务是串行的,执行完一个任务,再执行下一个任务 */- (void)syncSerial{  // 1.创建串行队列  dispatch_queue_t queue = dispatch_queue_create("com.kyle.queue", DISPATCH_QUEUE_SERIAL);    // 2.将任务加入队列  dispatch_sync(queue, ^{    NSLog(@"this is first %@",[NSThread currentThread]);  });  dispatch_sync(queue, ^{    NSLog(@"this is second %@",[NSThread currentThread]);  });  dispatch_sync(queue, ^{    NSLog(@"this is third %@",[NSThread currentThread]);  });}

5、异步函数 + 主队列

// * 异步函数 + 主队列:只在主线程中执行任务- (void)asyncMain{  // 1.获得主队列  dispatch_queue_t queue = dispatch_get_main_queue();  // 2.将任务加入队列  dispatch_async(queue, ^{    NSLog(@"this is first %@",[NSThread currentThread]);    NSLog(@"this is second %@",[NSThread currentThread]);    NSLog(@"this is third %@",[NSThread currentThread]);  });}

6、同步函数 + 主队列

// * 同步函数 + 主队列:- (void)syncMain{  NSLog(@"begin");    // 1.获得主队列  dispatch_queue_t queue = dispatch_get_main_queue();  // 2.将任务加入队列  dispatch_sync(queue, ^{    NSLog(@"this is %@",[NSThread currentThread]);      });  NSLog(@"end");}

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