多线程应用

GCD先执行ABC,都完成后再执行D

+(void)test1{
    //创建队列组
    dispatch_group_t group = dispatch_group_create();
    //进入这个组
    dispatch_group_enter(group);
    dispatch_group_async(group, dispatch_get_global_queue(0, 0), ^{
        NSLog(@"operationA---");
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(4 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            NSLog(@"operationA--OK-");
            //这个组的任务完成时离开
            dispatch_group_leave(group);
        });
    });
    dispatch_group_enter(group);
    dispatch_group_async(group, dispatch_get_global_queue(0, 0), ^{
        NSLog(@"operationB---");
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            NSLog(@"operationB--OK-");
            dispatch_group_leave(group);
        });
    });
    dispatch_group_enter(group);
    dispatch_group_async(group, dispatch_get_global_queue(0, 0), ^{
        NSLog(@"operationC---");
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            NSLog(@"operationC--OK-");
            dispatch_group_leave(group);
        });
    });
    //当所有的任务都完成后会发送这个通知
    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        NSLog(@"ABC 任务全部完成 ,开始D");
    });
}


打印:
2019-04-03 15:01:26.213596+0800 GCD[598:92227] operationB---
2019-04-03 15:01:26.214236+0800 GCD[598:92227] operationC---
2019-04-03 15:01:26.214450+0800 GCD[598:92225] operationA---
2019-04-03 15:01:28.368611+0800 GCD[598:92202] operationB--OK-
2019-04-03 15:01:29.488141+0800 GCD[598:92202] operationC--OK-
2019-04-03 15:01:30.572944+0800 GCD[598:92202] operationA--OK-
2019-04-03 15:01:30.573321+0800 GCD[598:92202] ABC 任务全部完成

NSOperation 先执行AB在执行C

+ (void)addDependency {
    
    // 1.创建队列
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    
    // 2.创建操作
    NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
        for (int i = 0; i < 2; i++) {
            [NSThread sleepForTimeInterval:2]; // 模拟耗时操作
            NSLog(@"1---%@", [NSThread currentThread]); // 打印当前线程
        }
    }];
    NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
        for (int i = 0; i < 2; i++) {
            [NSThread sleepForTimeInterval:2]; // 模拟耗时操作
            NSLog(@"2---%@", [NSThread currentThread]); // 打印当前线程
        }
    }];
    
    NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
        for (int i = 0; i < 2; i++) {
            [NSThread sleepForTimeInterval:2]; // 模拟耗时操作
            NSLog(@"3---%@", [NSThread currentThread]); // 打印当前线程
        }
    }];
    // 3.添加依赖
    [op3 addDependency:op1]; // 让op2 依赖于 op1，则先执行op1，在执行op2
       [op3 addDependency:op2];
//    // 4.添加操作到队列中
//    [queue addOperation:op1];
//    [queue addOperation:op2];
      [queue addOperations:@[op1 ,op2,op3] waitUntilFinished:YES];
}

打印:
2019-04-03 15:52:04.992320+0800 NSOperation[629:96844] 1---<NSThread: 0x15d48520>{number = 4, name = (null)}
2019-04-03 15:52:04.992329+0800 NSOperation[629:96845] 2---<NSThread: 0x15e42be0>{number = 3, name = (null)}
2019-04-03 15:52:06.993761+0800 NSOperation[629:96844] 1---<NSThread: 0x15d48520>{number = 4, name = (null)}
2019-04-03 15:52:06.993772+0800 NSOperation[629:96845] 2---<NSThread: 0x15e42be0>{number = 3, name = (null)}
2019-04-03 15:52:08.995584+0800 NSOperation[629:96844] 3---<NSThread: 0x15d48520>{number = 4, name = (null)}
2019-04-03 15:52:10.996866+0800 NSOperation[629:96844] 3---<NSThread: 0x15d48520>{number = 4, name = (null)}

觉得有用点个喜欢,谢谢!