GCD常用方法

GCD常用方法

//使用GCD创建多线程
-(void)initWithGCD
{
    //使用GCD创建多线程
    dispatch_queue_t groupBack=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

   dispatch_async(groupBack, ^{
       [self initWithSameRequest];
    });
   
    /*1 2 3 线程执行完 才开始执行4 5 6. 也就是说1 2 3 开始执行 4 5 6处于等待状态，1 2 3 执行完4 5 6马上进去执行*/
/*    dispatch_queue_t aDQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_group_t group = dispatch_group_create();
    dispatch_group_async(group, aDQueue, ^{
        NSLog(@"task 1 \n");
    });
    dispatch_group_async(group, aDQueue, ^{
        NSLog(@"task 2 \n");
    });
    dispatch_group_async(group, aDQueue, ^{
        NSLog(@"task 3 \n");
    });
    dispatch_group_wait(group, DISPATCH_TIME_FOREVER);//其他同类等待
    dispatch_release(group);
   
    NSLog(@"1 23 完成 4 5 6开始了");
   
   
    group = dispatch_group_create();
   
   
    dispatch_group_async(group, aDQueue, ^{
        NSLog(@"task 4 \n");
    });
    dispatch_group_async(group, aDQueue, ^{
        NSLog(@"task 5 \n");
    });
    dispatch_group_async(group, aDQueue, ^{
        NSLog(@"task 6 \n");
    });
   
    dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
    dispatch_release(group);*/
}

2.//使用GCD通知主线程执行
-(void)initWithGradeCenterDispatch
{
    dispatch_queue_t  Queue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_async(Queue, ^{
        NSURL * URL=[NSURL URLWithString:@"http://avatar.csdn.net/2/C/D/1_totogo2010.jpg"];
        NSData * DATA=[[NSData alloc]initWithContentsOfURL:URL];
        UIImage * image=[[UIImage alloc]initWithData:DATA];
       
        if (DATA!=nil)
        {
            //通知主线程更新界面
            dispatch_async(dispatch_get_main_queue(),
                           ^{
                               self.imageView.image=image;
                           });
           
        }
    });
}
3. //顺序执行
-(void)initDownLocation
{
    dispatch_queue_t  main=dispatch_queue_create("gcdtest.rongfzh.yc",DISPATCH_QUEUE_CONCURRENT);
    dispatch_async(main, ^{
        NSLog(@"任务1\n%@",[NSDate date]);
    });
    dispatch_async(main, ^{
        NSLog(@"任务2\n%@",[NSDate date]);
    });
    dispatch_barrier_async(main, ^{
        NSLog(@"任务3\n%@",[NSDate date]);
    });
    dispatch_async(main, ^{
        NSLog(@"任务4\n%@",[NSDate date]);
    });
      
}

//代码执行N次
-(void)Ntimes
{
    dispatch_queue_t groupBack=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_apply(5,groupBack, ^(size_t index)
    {
    // 执行5次
        NSLog(@"执行5次了吗");
    });
}
//创建一个同步请求
-(void)initWithSameRequest
{

    NSURL * url=[NSURL URLWithString:@"http://api.douban.com/book/subjects?q=%E4%B8%89&start-index=1&max-results=10&apikey=04f1ae6738f2fc450ed50b35aad8f4cf&alt=json"];
    ASIHTTPRequest * request=[[ASIHTTPRequest alloc]initWithURL:url];
  
    //设置是否按服务器在Header里指定的是否可被缓存或过期策略进行缓存:
    //[[ASIDownloadCache sharedCache]setShouldRespectCacheControlHeaders:NO];
    //设置缓存的有效时间 30天
    //[request setSecondsToCache:60*60*24*30];
    //判断能不能重缓存种读取
    //[request didUseCachedResponse];
    //设置缓存的路径
//    NSArray * path=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
//    NSString * docpath=[path objectAtIndex:0];
//    [request setDownloadDestinationPath:docpath];
    //设置缓存 把缓存数据永久保存在本 地,
    [request setCacheStoragePolicy:ASICachePermanentlyCacheStoragePolicy];
   
  // [request setDownloadDestinationPath:[[ ASIDownloadCache sharedCache ] pathToStoreCachedResponseDataForRequest:request ]];
    [request startSynchronous];//同步下载
    NSError * error=[request error];
    if (!error)
    {
        //NSString *
        NSDictionary * json=[request.responseData objectFromJSONData];
     
        NSArray * allBooks = [json objectForKey:@"entry"];
        for (NSDictionary * book in allBooks)
        {
            // model=[[BookModel alloc]init];
            //评论
            NSString * avger=[[book objectForKey:@"gd:rating"]objectForKey:@"@average"];
            // model.rating=[avger floatValue];
            NSLog(@"%f",[avger floatValue]);
            NSString * number=[[book objectForKey:@"gd:rating"]objectForKey:@"@numRaters"];
            // model.numRatings=[number intValue];
            NSLog(@"%d",[number intValue]);
            //书的名字
            NSString * titleName=[[book objectForKey:@"title"] objectForKey:@"$t"];
            NSLog(@"书的名字:  %@",titleName);
           
            //model.bookName=titleName;
            //        NSArray * authotArray=[book objectForKey:@"author"];
            //        for (NSDictionary *author in authotArray)
            //        {
            //            NSString * authorName=[[book objectForKey:@"name"] objectForKey:@"$t"];
            //            NSLog(@"作者的名字  :%@",authorName);
            //        }
           
            // NSString * categotyName=[[book objectForKey:@"category"]objectForKey:@"@scheme"];
            // NSLog(@"categoty %@",categotyName);
           
            NSArray * attribute=[book objectForKey:@"db:attribute"];
            for (NSDictionary * attributess in attribute)
            {
                NSString * attraName=[attributess objectForKey:@"@name"];
               
                if ([attraName isEqualToString:@"pubdate"])
                {
                    NSString * pubdate=[attributess objectForKey:@"$t"];
                    NSLog(@"pubdate %@",pubdate);
                }
                else if ([attraName isEqualToString:@"publisher"])
                {
                    NSString * publisher=[attributess objectForKey:@"$t"];
                    // model.publisher=publisher;
                    NSLog(@"publisher %@",publisher);
                }
                else if ([attraName isEqualToString:@"price"])
                {
                    NSString * price=[attributess objectForKey:@"$t"];
                    NSLog(@"price %@",price);
                    //价格
                    // model.price=price;
                }
                else if ([attraName isEqualToString:@"author"])
                {
                    NSString * author=[attributess objectForKey:@"$t"];
                    NSLog(@"author %@",author);
                    //作者的名字
                    // model.autherName=author;
                }
                else if ([attraName isEqualToString:@"translator"])
                {
                    NSString * translator=[attributess objectForKey:@"$t"];
                    NSLog(@"translator %@",translator);
                    //出版社
                    //model.translator=translator;
                }
               
               
               
            }
            NSArray * link=[book objectForKey:@"link"];
            for (NSDictionary * image in link)
            {
                NSString * str=[image objectForKey:@"@rel"];
                if ([str isEqualToString:@"image"])
                {
                    //图片
                    NSString * pubdate=[image objectForKey:@"@href"];
                    NSLog(@"pubdate %@",pubdate);
                    //model.iconUrl=pubdate;
                }
                else if([str isEqualToString:@"mobile"])
                {
                    NSString * mobile=[image objectForKey:@"@href"];
                    // model.introUrl=mobile;
                    NSLog(@"mobile %@",mobile);
                }
            }
           
           
           
        }
    

    }
    [self performSelectorOnMainThread:@selector(hello) withObject:nil waitUntilDone:YES];
[request release];
}
-(void)hello
{
    NSLog(@"下载完成,请主线程注意更新");
}
//创建一个异步请求
-(void)initWithDifferent
{
    NSURL * url1=[NSURL URLWithString:@"http://api.douban.com/book/subjects?q=%E4%B8%89&start-index=1&max-results=10&apikey=04f1ae6738f2fc450ed50b35aad8f4cf&alt=json"];
    ASIHTTPRequest * request=[[ASIHTTPRequest alloc]initWithURL:url1];
   // [request cancel];//取消异步请求 这个是取消所有的异步请求
   // [request clearDelegatesAndCancel];//如果不想调用delegate方法
    request.delegate=self;
    [request startAsynchronous];//异步下载
}