iOS网络: NSURLConnection进行异步请求

- (void)sendAsynNetWork{
    NSString *urlString = @"http://www.apple.com";
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];
    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    //发送异步请求
    [NSURLConnection sendAsynchronousRequest:urlRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
        if ([data length] > 0 && connectionError == nil) {
            NSString *html = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
            NSLog(@"HTML = %@",html);
            //保存从网络上下载的数据到你的硬盘中
            //1.获取存储路径
            NSString *documentsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0];
            //将文件名添加到存储路径上,形成文件路径
            NSString *filePath = [documentsDir stringByAppendingPathComponent:@"apple.html"];
            //将数据写入文件 存到硬盘
            [data writeToFile:filePath atomically:YES];
            NSLog(@"Successfully saved the file to %@",filePath);
        }
        else if ([data length] == 0 && connectionError == nil){
            NSLog(@"Nothing was downloaded");
        }
        else if (connectionError != nil){
            NSLog(@"connectionError happened = %@",connectionError);
        }
    }];
}