17.多线程

课程来自慕课网不死鸟fj老师

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pThread

- (void)clickPThread {
    NSLog(@"主线程");
    pthread_t pthread;
    pthread_create(&pthread, NULL, run, NULL);
    
}

void *run(void *data) {
    NSLog(@"子线程");
    for (int i = 1; i < 10; i++) {
        NSLog(@"%d",i);
        sleep(1);
    }
    return NULL;
}

NSThread的创建和执行

1. 通过 alloc init 方式创建并执行线程

    NSThread *thread1 = [[NSThread alloc] initWithTarget:self selector:@selector(runThread1) object:nil];
    [thread1 setName:@"Name_Thread1"];  // 设置线程名称
    [thread1 setThreadPriority:0.2];  // 设置线程优先级 0-1
    [thread1 start];

2. 通过 detachNewThreadSelector 方式创建并执行线程

    [NSThread detachNewThreadSelector:@selector(runThread1) toTarget:self withObject:nil];

3. 通过 performSelectorInBackground 方式创建线程

    [self performSelectorInBackground:@selector(runThread1) withObject:nil];

NSThread锁

-(void)sale {
    while (true) {
        @synchronized (self) {
            if (self.tickets > 0) {
                [NSThread sleepForTimeInterval:0.5];
                self.tickets--;
                self.soldCount = Total - self.tickets;
                NSLog(@"%@: 当前余票: %d, 售出: %d",[NSThread currentThread].name,self.tickets,self.soldCount);
            }
        }
    }
}

GCD的创建

    // 获取全局并发队列
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    // 获取主队列
    dispatch_queue_t mainQueue = dispatch_get_main_queue();

    dispatch_async(queue, ^{
        // 异步追加任务
        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
        }
        // 回到主线程
        dispatch_async(mainQueue, ^{
            // 追加在主线程中执行的任务
            [NSThread sleepForTimeInterval:2];              // 模拟耗时操作
            NSLog(@"2---%@",[NSThread currentThread]);      // 打印当前线程
        });
    });

// 串行队列的创建方法
dispatch_queue_t queue = dispatch_queue_create("com.test.gcd.queue", DISPATCH_QUEUE_SERIAL);
// 并发队列的创建方法
dispatch_queue_t queue = dispatch_queue_create("com.test.gcd.queue", DISPATCH_QUEUE_CONCURRENT);

GCD_Group

    NSLog(@"GCD开始执行");
    dispatch_queue_t queue = dispatch_queue_create("com.test.gcd.group", DISPATCH_QUEUE_CONCURRENT);
    dispatch_group_t group = dispatch_group_create();
    dispatch_group_enter(group);
    [self sendRequest1:^{
        NSLog(@"request1 done");
        dispatch_group_leave(group);
    }]
    [self sendRequest2:^{
        NSLog(@"request2 done");
        dispatch_group_leave(group);
    }]
//    dispatch_group_async(group, queue, ^{
//        NSLog(@"start task 1");
//        [NSThread sleepForTimeInterval:2];
//        NSLog(@"end task 1");
//    });
//    dispatch_group_async(group, queue, ^{
//        NSLog(@"start task 2");
//        [NSThread sleepForTimeInterval:2];
//        NSLog(@"end task 2");
//    });
    dispatch_group_notify(group, queue, ^{
        NSLog(@"All tasks over");
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"回到主线程刷新UI");
        });
    });

NSOperation

NSOperation是个抽象类,并不具备封装操作的能力,必须使⽤它的子类
使用NSOperation⼦类的方式有3种：
（1）NSInvocationOperation
（2）NSBlockOperation
（3）自定义子类继承NSOperation,实现内部相应的⽅法