NSOperation

• NSOperation是个抽象类，不具备封操作的能力，必须使用它的子类

  • 使用NSOperation子类的方式有两种

  • NSInvocationOperation

  • NSBlockOperation

• NSInvocationOperation

NSInvocationOperation *op1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(download1) object:nil];
    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [queue addOperation:op1];

• NSBlockOperation

NSBlockOperation *blockOp1 = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"blockOp1-----%@",[NSThread currentThread]);
    }];
    /*
     NSOperation:
     主队列:   [NSOperationQueue mainQueue] 和GCD中的主队列一样,串行队列
     非主队列: [[NSOperationQueue alloc]init]  非常特殊(同时具备并发和串行的功能)
     //默认情况下,非主队列是并发队列
     */
    NSOperationQueue *queue = [NSOperationQueue mainQueue];
    
    //追加任务
    [blockOp1 addExecutionBlock:^{
        NSLog(@"4----%@",[NSThread currentThread]);
    }];
    [queue addOperation:blockOp1];

• 自定义NSOperation

  • 自定义NSOperation的时候需要重写-(void)main方法,在main方法中封装任务

    XCOperation *op1 = [[XCOperation alloc]init];
    NSOperationQueue *queue =[[NSOperationQueue alloc]init];
    [queue addOperation:op1];
    ```- ###NSIOperation 暂停||取消||最大并发数量
    
    

• 最大并发数量

/**
     *  设置最大并发数量 maxConcurrentOperationCount
     同一时间最多有多少个任务可以执行
     串行执行任务!=只开一条线程 (线程同步)
     maxConcurrentOperationCount >1 那么就是并发队列
     maxConcurrentOperationCount == 1 那就是串行队列
     maxConcurrentOperationCount == 0  不会执行任务
     maxConcurrentOperationCount == -1 特殊意义 最大值 表示不受限制
     */
    self.queue.maxConcurrentOperationCount = 1;

• 暂停 取消

- (IBAction)strartButtonClick:(id)sender
{
    self.queue = [[NSOperationQueue alloc]init];
    
    self.queue.maxConcurrentOperationCount = 1;

    NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
        for (NSInteger i = 0; i <1000; i++) {
           NSLog(@"op1----%zd-----%@",i,[NSThread currentThread]);
        }
        
    }];
    NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
        for (NSInteger i = 0; i <1000; i++) {
            NSLog(@"op2----%zd-----%@",i,[NSThread currentThread]);
        }
    }];
    NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
        for (NSInteger i = 0; i <1000; i++) {
            NSLog(@"op3----%zd-----%@",i,[NSThread currentThread]);
        }
    }];
    [self.queue addOperation:op1];
    [self.queue addOperation:op2];
    [self.queue addOperation:op3];
    
}
/**
 *  暂停
    不能暂停当前正在处于执行状态的任务，比如现在有个循环100次，如果执行了暂停，只能在循环100次结束后暂停
 */
- (IBAction)supendedButtonClick:(id)sender
{
    [self.queue setSuspended:YES];
    
}
/**
 *  继续
 */
- (IBAction)continueButtonClick:(id)sender
{
    [self.queue setSuspended:NO];
}
/**
 *  取消,不可以恢复
    该方法内部调用了所有操作的cancel方法
 */
- (IBAction)cancleButtonClick:(id)sender
{
    //取消所有线程任务
    [self.queue cancelAllOperations];
}

• 操作依赖和监听

NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    NSOperationQueue *queue2 =[[NSOperationQueue alloc]init];
    NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"1---%@",[NSThread currentThread]);
    }];
    
    NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"2---%@",[NSThread currentThread]);
    }];
    NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"3---%@",[NSThread currentThread]);
    }];
    NSBlockOperation *op4 = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"4---%@",[NSThread currentThread]);
    }];
    //线程1 依赖于 线程4   依赖可以跨线程
    [op1 addDependency:op4];
    //线程4 依赖于 线程2
    [op4 addDependency:op2];
    //线程2 依赖于 线程3
    [op2 addDependency:op3];
    //执行结果 3->2->4->1
    
    /**
     *  不可以循环依赖
     [op1 addDependency:op4];
     [op4 addDependency:op1];
     这样谁都不会执行
     */
    
    //操作监听 在执行这个block块的时候有可能调用同一条线程,也有可能不是
    op3.completionBlock = ^{
        NSLog(@"++++++%@",[NSThread currentThread]);
    };
    [queue addOperation:op1];
    [queue addOperation:op2];
    [queue addOperation:op3];
    [queue2 addOperation:op4];

• NSOpreation线程通信

 NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    NSBlockOperation *download1 = [NSBlockOperation blockOperationWithBlock:^{
        NSURL *url = [NSURL URLWithString:@"http://4493bz.1985t.com/uploads/allimg/150127/4-15012G52133.jpg"];
        NSData *data = [NSData dataWithContentsOfURL:url];
        self.image1 = [UIImage imageWithData:data];
        NSLog(@"download1----%@",[NSThread currentThread]);
        
    }];
    NSBlockOperation *download2 = [NSBlockOperation blockOperationWithBlock:^{
        NSURL *url = [NSURL URLWithString:@"http://4493bz.1985t.com/uploads/allimg/150127/4-15012G52133.jpg"];
        NSData *data = [NSData dataWithContentsOfURL:url];
        self.image2 = [UIImage imageWithData:data];
        NSLog(@"download2----%@",[NSThread currentThread]);
        
    }];
    NSBlockOperation *configQueue =[NSBlockOperation blockOperationWithBlock:^{
        self.imageView1.alpha = 0.8;
        self.imageView1.alpha = 0.5;
        
        //在主线程中更新UI
        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            self.imageView1.image = self.image1;
            self.imageView2.image = self.image2;
            NSLog(@"UI----%@",[NSThread currentThread]);
        }];
    }];
    //添加依赖
    [configQueue addDependency:download1];
    [configQueue addDependency:download2];
    
    [queue addOperation:download1];
    [queue addOperation:download2];
    [queue addOperation:configQueue];

• 自定义NSOperation类

  • NSOperation 的 addOperation方法默认会先调用strat方法，在strat内部会调用main方法，所以当我们自定义一个NSOperation类的时候，重写strat方法或者main都可以。NSThread是通过main方法封装