IOS之－－－－－－下载图片

（1）请求图片的操作

[NSThread detachNewThreadSelector:@selector(imageResourceRequest:) toTarget:self withObject:url];

（2）执行下载图片的函数

//请求图片资源
-(void)imageResourceRequest:(NSString *)url
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    //根据网络数据，获得到image资源
    NSData  *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:url]];
    UIImage *image = [[UIImage alloc] initWithData:data];
   
    
    if(image == nil){
    }else {
         NSMutableDictionary *mutable = [[NSMutableDictionary alloc]init];
        [mutable setObject:url forKey:@"url"];
        [mutable setObject:image forKey:@"data"];
        //回到主线程，显示图片信息

        [self performSelectorOnMainThread:@selector(displayImage:) withObject:mutable waitUntilDone:NO];
    }
    

    
    [data release];
    [image release];
    
    [pool release];
}

（3）显示图片

//显示图片信息
-(void)displayImage:(NSMutableDictionary *)imageDataDictionary
{
    UIImage* image = (UIImage *)[imageDataDictionary objectForKey:@"data"];
    NSString* url = (NSString *)[imageDataDictionary objectForKey:@"url"];
    [FlowerPicData instanceAddObject:url : image];
    [_gridView reloadData];
    [imageDataDictionary release];
}