NSOperation实现线程间通信

 -(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

 {

     //1.创建队列

     NSOperationQueue *queue= [[NSOperationQueue alloc]init];

     NSBlockOperation *download1 = [NSBlockOperation blockOperationWithBlock:^{

         //2.1.确定要下载网络图片的url地址，一个url唯一对应着网络上的一个资源

         NSURL *url = [NSURL URLWithString:@"http://p6.qhimg.com/t01d2954e2799c461ab.jpg"];

         //2.2.根据url地址下载图片数据到本地（二进制数据)

         NSData *data = [NSData dataWithContentsOfURL:url];

         //2.3.把下载到本地的二进制数据转换成图片

        self.image1 = [UIImage imageWithData:data];

     }];

     NSBlockOperation *download2 = [NSBlockOperation blockOperationWithBlock:^{

         //2.1.确定要下载网络图片的url地址，一个url唯一对应着网络上的一个资源

         NSURL *url = [NSURL URLWithString:@"http://p6.qhimg.com/t01d2954e2799c461ab.jpg"];

         //2.2.根据url地址下载图片数据到本地（二进制数据)

         NSData *data = [NSData dataWithContentsOfURL:url];

         //2.3.把下载到本地的二进制数据转换成图片

         self.image2 = [UIImage imageWithData:data];

     }];

     NSBlockOperation *combie = [NSBlockOperation blockOperationWithBlock:^{

         UIGraphicsBeginImageContext(CGSizeMake(, ));

         [self.image1 drawInRect:CGRectMake(, , , )];

         [self.image2 drawInRect:CGRectMake(, , , )];

         UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

         UIGraphicsEndImageContext();

         //刷新UI

         [[NSOperationQueue mainQueue] addOperationWithBlock:^{

             self.imageView.image = image;

             NSLog(@"%@----",[NSThread currentThread]);

         }];

     }];

     [combie addDependency:download1];

     [combie addDependency:download2];

     [queue addOperation:download1];

     [queue addOperation:download2];

     [queue addOperation:combie];

 }

示例