基本代码

NSInvocationOperation

start

• start 方法 会在当前线程执行 @selector 方法

NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@"Invocation"];

// start方法 会在当前线程执行 @selector 方法
[op start];

- (void)downloadImage:(id)obj {
    NSLog(@"%@ %@", [NSThread currentThread], obj);
}

添加到队列

将操作添加到队列，会"异步"执行 selector 方法

- (void)opDemo2 {
    NSOperationQueue *q = [[NSOperationQueue alloc] init];

    NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@"queue"];

    [q addOperation:op];
}

添加多个操作

- (void)opDemo3 {
    NSOperationQueue *q = [[NSOperationQueue alloc] init];

    for (int i = 0; i < 10; ++i) {
        NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@(i)];

        [q addOperation:op];
    }
}

执行效果：会开启多条线程，而且不是顺序执行。

NSBlockOperation

- (void)opDemo4 {
    NSOperationQueue *q = [[NSOperationQueue alloc] init];

    NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"%@", [NSThread currentThread]);
    }];

    [q addOperation:op];
}

更简单的，直接添加 Block

- (void)opDemo5 {
    NSOperationQueue *q = [[NSOperationQueue alloc] init];

    for (int i = 0; i < 10; ++i) {
        [q addOperationWithBlock:^{
            NSLog(@"%@ %d", [NSThread currentThread], i);
        }];
    }
}

向队列中添加不同的操作

- (void)opDemo5 {
    NSOperationQueue *q = [[NSOperationQueue alloc] init];

    for (int i = 0; i < 10; ++i) {
        [q addOperationWithBlock:^{
            NSLog(@"%@ %d", [NSThread currentThread], i);
        }];
    }

    NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"block %@", [NSThread currentThread]);
    }];
    [q addOperation:op1];

    NSInvocationOperation *op2 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@"invocation"];
    [q addOperation:op2];
}

CompletionBlock 属性

// 设置完成回调
[op setCompletionBlock:^{
    NSLog(@"完成 %@", [NSThread currentThread]);
}];

• 只要设置了 CompletionBlock，当操作执行完毕后，就会被自动调用

• CompletionBlock 既不在主线程也不在操作执行所在线程

  ​

线程间通讯

//@property (class, readonly, strong, nullable) NSOperationQueue *currentQueue;
  //@property (class, readonly, strong) NSOperationQueue *mainQueue;

- (void)opDemo6 {
    NSOperationQueue *q = [[NSOperationQueue alloc] init];

    [q addOperationWithBlock:^{
        NSLog(@"耗时操作 %@", [NSThread currentThread]);

        // 主线程更新 UI
        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            NSLog(@"更新 UI %@", [NSThread currentThread]);
        }];
    }];
}