使用NSURLSession的异步上载不起作用,但同步NSURLConnection会起作用

你是对的,如果你只想让你的请求异步,你应该退休sendSynchronousRequest.虽然我们曾经推荐过sendAsynchronousRequest,有效的iOS 9 NSURLConnection正式弃用,但我们应该赞成NSURLSession.

一旦你开始使用NSURLSession,你可能会发现自己被它所吸引.例如,[NSURLSessionConfiguration backgroundSessionConfiguration:]即使应用程序进入后台,也可以使用a ,然后上传进度.(你必须编写一些委托方法,所以为了简单起见,我在下面进行了一个简单的前台上传.)这只是你的业务需求的问题,抵消了新NSURLSession功能与它所需的iOS 7+限制.

顺便说一下,如果没有AFNetworking的引用,任何有关iOS/MacOS中网络请求的对话可能都是不完整的.它极大地简化了这些多部分请求的创建,绝对值得调查.他们也有NSURLSession支持(但我没有使用他们的会话包装,所以不能说它).但AFNetworking毫无疑问值得您考虑.您可以享受基于委托的API的丰富功能(例如,进度更新,可取消请求,操作之间的依赖关系等),提供更好的控制,可通过便利方法(如sendSynchronousRequest),但不会拖延你的杂草委托方法本身.

无论如何,如果您真的对如何进行上传感兴趣NSURLSession,请参阅下文.

如果你想上传NSURLSession,那么思考就会略有转变,即在请求NSMutableURLRequest主体的创建中分离请求的配置(和它的头部)(你现在在实例化期间指定)NSURLSessionUploadTask).您现在指定为上载任务的一部分的请求正文可以是a NSData,文件或流(我使用NSData下面的代码,因为我们正在构建一个多部分请求):

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"POST"];
NSString *boundary = [self boundaryString];
[request addValue:[NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary] forHTTPHeaderField:@"Content-Type"];

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];

NSData *fileData = [NSData dataWithContentsOfFile:path];
NSData *data = [self createBodyWithBoundary:boundary username:@"rob" password:@"password" data:fileData filename:[path lastPathComponent]];

NSURLSessionUploadTask *task = [session uploadTaskWithRequest:request fromData:data completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    NSAssert(!error, @"%s: uploadTaskWithRequest error: %@", __FUNCTION__, error);

    // parse and interpret the response `NSData` however is appropriate for your app
}];
[task resume];

NSData发送的创建与您现有的代码非常相似:

- (NSData *) createBodyWithBoundary:(NSString *)boundary username:(NSString*)username password:(NSString*)password data:(NSData*)data filename:(NSString *)filename
{
    NSMutableData *body = [NSMutableData data];

    if (data) {
        //only send these methods when transferring data as well as username and password
        [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
        [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"file\"; filename=\"%@\"\r\n", filename] dataUsingEncoding:NSUTF8StringEncoding]];
        [body appendData:[[NSString stringWithFormat:@"Content-Type: %@\r\n\r\n", [self mimeTypeForPath:filename]] dataUsingEncoding:NSUTF8StringEncoding]];
        [body appendData:data];
        [body appendData:[@"\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
    }

    [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"username\"\r\n\r\n%@\r\n", username] dataUsingEncoding:NSUTF8StringEncoding]];

    [body appendData:[[NSString stringWithFormat:@"--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"password\"\r\n\r\n%@\r\n", password] dataUsingEncoding:NSUTF8StringEncoding]];

    [body appendData:[[NSString stringWithFormat:@"--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];

    return body;
}

你硬编码边界和mime类型,这很好,但上面碰巧使用以下方法:

- (NSString *)boundaryString
{
    NSString *uuidStr = [[NSUUID UUID] UUIDString];

    // If you need to support iOS versions prior to 6, you can use
    // Core Foundation UUID functions to generate boundary string
    //
    // adapted from http://developer.apple.com/library/ios/#samplecode/SimpleURLConnections
    //
    // NSString  *uuidStr;
    //
    // CFUUIDRef uuid = CFUUIDCreate(NULL);
    // assert(uuid != NULL);
    // 
    // NSString  *uuidStr = CFBridgingRelease(CFUUIDCreateString(NULL, uuid));
    // assert(uuidStr != NULL);
    // 
    // CFRelease(uuid);

    return [NSString stringWithFormat:@"Boundary-%@", uuidStr];
}

- (NSString *)mimeTypeForPath:(NSString *)path
{
    // get a mime type for an extension using MobileCoreServices.framework

    CFStringRef extension = (__bridge CFStringRef)[path pathExtension];
    CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, extension, NULL);
    assert(UTI != NULL);

    NSString *mimetype = CFBridgingRelease(UTTypeCopyPreferredTagWithClass(UTI, kUTTagClassMIMEType));
    assert(mimetype != NULL);

    CFRelease(UTI);

    return mimetype;
}