iOS NSOperation学习

 1   NSBlockOperation *operationA = [NSBlockOperation blockOperationWithBlock:^{
 2         for (int i = 0; i<100; i++) {
 3             NSLog(@"-operation-下载图片-%@",[NSThread currentThread]);
 4         }
 5     }];
 6 
 7     operationA.completionBlock = ^{
 8         NSLog(@"--开始下载第二张图片--%@",[NSThread currentThread]);
 9     };
10 
11     NSLog(@"--现在在干嘛--%@",[NSThread currentThread]);
12 
13     NSOperationQueue *queue = [[NSOperationQueue alloc] init];
14     [queue addOperation:operationA];

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];