iOS NSOperation学习

为什么要用NSOperation？为什么不用GCD

在我认为NSOperation的优点是可控制性的，可以随时断开，暂停线程

  NSBlockOperation *operationA = [NSBlockOperation blockOperationWithBlock:^{
        for (int i = 0; i<100; i++) {
            NSLog(@"-operation-下载图片-%@",[NSThread currentThread]);
        }
    }];

    operationA.completionBlock = ^{
        NSLog(@"--开始下载第二张图片--%@",[NSThread currentThread]);
    };

    NSLog(@"--现在在干嘛--%@",[NSThread currentThread]);

    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    [queue addOperation:operationA];

 

NSOperation添加线程依赖

NSInvocationOperation *operation1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(operationA:) object:nil];
    NSInvocationOperation *operation2 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(operationB:) object:nil];

    NSBlockOperation *operation3 = [NSBlockOperation blockOperationWithBlock:^{
        for (int i = 0; i<10; i++) {
            NSLog(@"NSBlockoperation3=--1-----%@",[NSThread currentThread]);
        }
    }];
    [operation3 addExecutionBlock:^{
        for (int i = 0; i<10; i++) {
            NSLog(@"NSBlockoperation3=--2-----%@",[NSThread currentThread]);
        }
    }];

    //添加依赖  不能相互依赖
    [operation1 addDependency:operation2];
    [operation2 addDependency:operation3];

    //创建NSOperationQueue
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    [queue addOperation:operation1];
    [queue addOperation:operation2];
    [queue addOperation:operation3];