OC 线程操作3 - NSOperation 实现线程间通信

#import "ViewController.h"

@interface ViewController ()

/**
 图片
 */
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
//    [self downloadImage];
    [self downloadImagAndCompoundIma];
}


/**
 下载图片 并且合成

 

 */
-(void)downloadImagAndCompoundIma{
    
    /*
     获取图片属性1：搞两个属性 然后self.img1, self.img2
     获取图片属性2: 使用__blcok修饰，
     */
    __block UIImage *ima1 = [[UIImage alloc] init];
    __block UIImage *ima2 = [[UIImage alloc] init];
    
    //1.创建 非主队列
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    
    //2.创建任务 : 下载图片1
    NSBlockOperation *op1 =  [NSBlockOperation blockOperationWithBlock:^{
        
        NSString *urlStr = [NSString stringWithFormat:@"http://pic.90sjimg.com/design/00/07/85/23/58ef8faf71ffe.png"];
        NSURL *url = [NSURL URLWithString:urlStr];
        NSData *data = [NSData dataWithContentsOfURL:url];
        ima1 = [UIImage imageWithData:data];
    }];
    
    //3.创建任务 : 下载图片2
    NSBlockOperation * op2 = [NSBlockOperation blockOperationWithBlock:^{
        // 下载图片
        NSString *urlStr = [NSString stringWithFormat:@"http://pic28.nipic.com/20130330/9607253_143631959000_2.png"];
        NSURL *url = [NSURL URLWithString:urlStr];
        NSData *data = [NSData dataWithContentsOfURL:url];
        ima2 = [UIImage imageWithData:data];
    }];
    
    //4.合成图片
    NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
        //1。开启图形上下文 并且设置上下文 宽高
        UIGraphicsBeginImageContext(CGSizeMake(200, 200));
        
        //2.图片画图
        [ima1 drawInRect:CGRectMake(0, 0, 100, 200)];
        ima1 = nil;
        
        [ima2 drawInRect:CGRectMake(100, 0, 100, 200)];
        ima2 = nil;
        
        //3.根据图形上下文去图片
        UIImage *ima = UIGraphicsGetImageFromCurrentImageContext();
        
        //4.关闭上下文
        UIGraphicsEndImageContext();
        //3.回到主线程刷新UI
        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            self.imageView.image = ima;
        }];
    }];
    
    //5.添加依赖，因为全都是异步执行 谁先谁后不可控
    [op3 addDependency:op1];
    [op3 addDependency:op2];
    
    //3.添加任务
    [queue addOperation:op1];
    [queue addOperation:op2];
    [queue addOperation:op3];
}



/**
 下载图片

 

 */
-(void)downloadImage{
    
    //1.创建 非主队列
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];

    //2.创建任务
    NSBlockOperation *op1 =  [NSBlockOperation blockOperationWithBlock:^{
       
        //2.1 下载图片
        NSString *urlStr = [NSString stringWithFormat:@"http://pic.90sjimg.com/design/00/07/85/23/58ef8faf71ffe.png"];
        NSURL *url = [NSURL URLWithString:urlStr];
        NSData *data = [NSData dataWithContentsOfURL:url];
        UIImage *ima = [UIImage imageWithData:data];
        
        //3.回到主线程刷新UI
        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            self.imageView.image = ima;
        }];
        
    }];
    
    //3.添加任务
    [queue addOperation:op1];
}
@end