OC 线程操作3 - NSOperation 实现线程间通信

  1 #import "ViewController.h"
  2
  3 @interface ViewController ()
  4
  5 /**
  6  图片
  7  */
  8 @property (weak, nonatomic) IBOutlet UIImageView *imageView;
  9
 10 @end
 11
 12 @implementation ViewController
 13 - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
 14 //    [self downloadImage];
 15     [self downloadImagAndCompoundIma];
 16 }
 17
 18
 19 /**
 20  下载图片 并且合成

 21  */
 22 -(void)downloadImagAndCompoundIma{
 23
 24     /*
 25      获取图片属性1：搞两个属性 然后self.img1, self.img2
 26      获取图片属性2: 使用__blcok修饰，
 27      */
 28     __block UIImage *ima1 = [[UIImage alloc] init];
 29     __block UIImage *ima2 = [[UIImage alloc] init];
 30
 31     //1.创建 非主队列
 32     NSOperationQueue *queue = [[NSOperationQueue alloc] init];
 33
 34     //2.创建任务 : 下载图片1
 35     NSBlockOperation *op1 =  [NSBlockOperation blockOperationWithBlock:^{
 36
 37         NSString *urlStr = [NSString stringWithFormat:@"http://pic.90sjimg.com/design/00/07/85/23/58ef8faf71ffe.png"];
 38         NSURL *url = [NSURL URLWithString:urlStr];
 39         NSData *data = [NSData dataWithContentsOfURL:url];
 40         ima1 = [UIImage imageWithData:data];
 41     }];
 42
 43     //3.创建任务 : 下载图片2
 44     NSBlockOperation * op2 = [NSBlockOperation blockOperationWithBlock:^{
 45         // 下载图片
 46         NSString *urlStr = [NSString stringWithFormat:@"http://pic28.nipic.com/20130330/9607253_143631959000_2.png"];
 47         NSURL *url = [NSURL URLWithString:urlStr];
 48         NSData *data = [NSData dataWithContentsOfURL:url];
 49         ima2 = [UIImage imageWithData:data];
 50     }];
 51
 52     //4.合成图片
 53     NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
 54         //1。开启图形上下文 并且设置上下文 宽高
 55         UIGraphicsBeginImageContext(CGSizeMake(200, 200));
 56
 57         //2.图片画图
 58         [ima1 drawInRect:CGRectMake(0, 0, 100, 200)];
 59         ima1 = nil;
 60
 61         [ima2 drawInRect:CGRectMake(100, 0, 100, 200)];
 62         ima2 = nil;
 63
 64         //3.根据图形上下文去图片
 65         UIImage *ima = UIGraphicsGetImageFromCurrentImageContext();
 66
 67         //4.关闭上下文
 68         UIGraphicsEndImageContext();
 69         //3.回到主线程刷新UI
 70         [[NSOperationQueue mainQueue] addOperationWithBlock:^{
 71             self.imageView.image = ima;
 72         }];
 73     }];
 74
 75     //5.添加依赖，因为全都是异步执行 谁先谁后不可控
 76     [op3 addDependency:op1];
 77     [op3 addDependency:op2];
 78
 79     //3.添加任务
 80     [queue addOperation:op1];
 81     [queue addOperation:op2];
 82     [queue addOperation:op3];
 83 }
 84
 85 
 86 /**
 87  下载图片

 88  */
 89 -(void)downloadImage{
 90
 91     //1.创建 非主队列
 92     NSOperationQueue *queue = [[NSOperationQueue alloc] init];
 93
 94     //2.创建任务
 95     NSBlockOperation *op1 =  [NSBlockOperation blockOperationWithBlock:^{
 96
 97         //2.1 下载图片
 98         NSString *urlStr = [NSString stringWithFormat:@"http://pic.90sjimg.com/design/00/07/85/23/58ef8faf71ffe.png"];
 99         NSURL *url = [NSURL URLWithString:urlStr];
100         NSData *data = [NSData dataWithContentsOfURL:url];
101         UIImage *ima = [UIImage imageWithData:data];
102
103         //3.回到主线程刷新UI
104         [[NSOperationQueue mainQueue] addOperationWithBlock:^{
105             self.imageView.image = ima;
106         }];
107
108     }];
109
110     //3.添加任务
111     [queue addOperation:op1];
112 }
113 @end

原文地址：https://www.cnblogs.com/qingzZ/p/9262639.html