码农公寓

关于NSURLSession的上传和下载

在iOS7.0后，苹果公司新推出了一个NSURLSession来代替NSURLConnection。NSURLConnection默认是在 主线程执行的。而NSURLSession是在其他线程上执行的。本篇主要实现了下载和上传，比起NSURLConnection更加简单。线程控制掌握 更加清晰。

#pragma mark -下载

- (IBAction)DownLoad

{

    //1.URL 

    NSString *urlStr = @"http://she.21cn.com/emotions/mingren/a/2014/0309/15/26645767.shtml";

    NSURL *url = [NSURL URLWithString:urlStr];

    

    //2.NSURLRequest

    NSURLRequest *request = [NSURLRequestrequestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicytimeoutInterval:5.0];

    

    //3.NSURLSession

    NSURLSession *session = [NSURLSessionsharedSession];

    

    NSURLSessionDownloadTask *downLoad = [session downloadTaskWithRequest:request completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {

        if (error) {

            NSLog(@"error = %@",error.localizedDescription);

        }else{

            // location是下载的临时文件目录

            NSLog(@"%@", location);

            

            // 如果要保存文件,需要将文件保存至沙盒

            // 1. 根据URL获取到下载的文件名

            NSString *fileName = [urlStr lastPathComponent];

            

            // 2. 生成沙盒的路径

            NSArray *docs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

            NSString *path = [docs[0] stringByAppendingPathComponent:fileName];

            NSURL *toURL = [NSURL fileURLWithPath:path];

            

            // 3. 将文件从临时文件夹复制到沙盒,在iOS中所有的文件操作都是使用NSFileManager

            [[NSFileManager defaultManager] copyItemAtURL:location toURL:toURL error:nil];

            

            // 4. 将图像设置到UIImageView

      

            dispatch_async(dispatch_get_main_queue(), ^{

                UIImage *image = [[UIImage alloc] initWithContentsOfFile:path];

                _imageView.image = image;

            });

        }

    }];

    

//4.因为任务默认是挂起状态，需要恢复任务（执行任务）

    [downLoad resume];

}

 

#pragma mark -上传

- (IBAction)upLoad

{

    // 0. 判断imageView是否有内容

    if (_imageView.image == nil) {

        NSLog(@"image view is empty");

        

        return;

    }

    

    // 0. 上传之前在界面上添加指示符

    UIActivityIndicatorView *indicator = [[UIActivityIndicatorViewalloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

    // 设置位置???

    CGSize size = _imageView.bounds.size;

    indicator.center = CGPointMake(size.width / 2.0, size.height / 2.0);

    

    [self.imageView addSubview:indicator];

    [indicator startAnimating];

    

    // 1. URL

    NSString *urlStr = @"http://192.168.3.251/uploads/123.jpg";

    NSURL *url = [NSURL URLWithString:urlStr];

    

    // 2. Request -> PUT,request的默认操作是GET

    NSMutableURLRequest *request = [NSMutableURLRequestrequestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicytimeoutInterval:5.0f];

    request.HTTPMethod = @"PUT";

    

    // *** 设置网络请求的身份验证! ***

    // 1> 授权字符串

    NSString *authStr = @"admin:123456";

    // 2> BASE64的编码,避免数据在网络上以明文传输

    // iOS中,仅对NSData类型的数据提供了BASE64的编码支持

    NSData *authData = [authStr dataUsingEncoding:NSUTF8StringEncoding];

    NSString *encodeStr = [authData base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithCarriageReturn];

    

    NSString *authValue = [NSString stringWithFormat:@"Basic %@", encodeStr];

    [request setValue:authValue forHTTPHeaderField:@"Authorization"];

    

    // 3. Session

    NSURLSession *session = [NSURLSessionsharedSession];

    

    // 4. UploadTask

    NSData *imageData = UIImageJPEGRepresentation(_imageView.image, 0.75);

    NSURLSessionUploadTask *upload = [session uploadTaskWithRequest:request fromData:imageData completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

        

        // 上传完成后,data参数转换成string就是服务器返回的内容

        NSString *str = [[NSStringalloc] initWithData:data encoding:NSUTF8StringEncoding];

        NSLog(@"OK -> %@", str);

        

        if (error != nil) {

            NSLog(@"ERROR -> %@", error.localizedDescription);

        } else {

            

        }

        

        [NSThreadsleepForTimeInterval:5.0f];

        

        dispatch_async(dispatch_get_main_queue(), ^{

            [indicator stopAnimating];

            

            [indicator removeFromSuperview];

        });

    }];

    

    [upload resume];

}