php – AFNetworking 2.0 POST问题,Cocoa错误3840(JSON文本没有以数组开头……)

Error Domain = NSCocoaErrorDomain Code = 3840 "The operation Couldn’t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo = 0x15d7bdd0 {NSDebugDescription = JSON text did not start with array or object and option to allow fragments not set.}

我的应用程序试图将JSON POST请求发送到api.PHP是一个使用AFNetworking 2的iOS应用程序

这是我的请求代码：

- (void)postUpdateRequest
{
    if (!dataModel)
        dataModel = [[DataModel alloc] init];

    NSDictionary *params = @{@"foo": @"bar2"};

    NSLog(@"%@",params);

/*    NSDictionary *params = @{@"cmd":@"update",@"user_id":[dataModel userId],@"token":[dataModel devicetoken]
                             };//@"ip_address":[dataModel getIPAddress]};*/

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
//    manager.requestSerializer = [AFJSONRequestSerializer serializer];

    [manager POST:ServerApiURL parameters:params success:^(AFHTTPRequestOperation *operation,id responSEObject) {
        NSLog(@"JSON: %@",responSEObject);
    } failure:^(AFHTTPRequestOperation *operation,NSError *error) {
        NSLog(@"Error: %@",error);
    }];
}

我查看了整个互联网,但无法找到我的具体问题的答案.
无论我做什么,我都会得到同样的错误.

为什么我的JSON格式不正确？我似乎也找不到嗅探我实际发送的JSON的方法.

谢谢.