适用于iOS 8扩展的AFNetworking后台会话配置

我目前正在开发iOS 8 App扩展程序,并且最后一篇文章遇到了困难.在我的应用程序的其余部分,我使用AFHTTPSessionManager子类,我实例化如下:

+ (MYAPIClient *)sharedClient {
    static MYAPIClient *_sharedClient = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedClient = [[MYAPIClient alloc] initWithBaseURL:[NSURL URLWithString:kMYBaseURL]];
        _sharedClient.requestSerializer = [[MYAPIRequestSerializer alloc] init];
        _sharedClient.responseSerializer = [[MYAPIResponseSerializer alloc] init];
    });
    return _sharedClient;
}

当我刚刚使用这个常规API客户端时,只需在共享扩展中发布一些文本就可以了,它甚至可以用于图像(虽然通常会失败),但我知道我需要使用后台会话配置.所以我用一个像这样的后台配置设置制作了一个非常相似的api客户端:

+ (MYAPIClient *)sharedBackgroundClient {
    static MYAPIClient *_sharedClient = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{

        NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"com.me.myapp.backgroundconfiguration"];
        _sharedClient = [[MYAPIClient alloc] initWithBaseURL:[NSURL URLWithString:kMYBaseURL] sessionConfiguration:sessionConfiguration];
        _sharedClient.requestSerializer = [[MYAPIRequestSerializer alloc] init];
        _sharedClient.responseSerializer = [[MYAPIResponseSerializer alloc] init];
    });
    return _sharedClient;
}

问题是,当我使用这个客户端进行POST时,我每次都会得到这些错误.

Aug 21 19:19:07 MY-iPhone Share[6290] : Attempted to create a task in a session that has been invalidated
Aug 21 19:19:07 MY-iPhone Share[6290] : *** Assertion failure in -[MYAPIClient setDelegate:forTask:], /Users/me/Documents/myproject/myproduct/Pods/AFNetworking/AFNetworking/AFURLSessionManager.m:337
Aug 21 19:19:07 MY-iPhone Share[6290] : *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid parameter not satisfying: task' 

有关如何使其工作的任何建议？非常感谢.