iOS post请求时报错NSLocalizedDescription=Expected status code in (200-299), got 400

用AFNetworking postJSON数据的时候，刚开始提示我//Error Domain=NSURLErrorDomain Code=-1007 "too many HTTP redirects"，说是多重定向问题

后来我改了之后又报错//NSLocalizedDescription=Expected status code in (200-299), got 400

解决办法：

   NSString *pathStr=@"http://api.XXX.com/provider" ;
    
    NSDictionary *jsonObject = @{@"key":@"d85c713ef6704d651c7ce",@"userId":@"123456654321"};
    
    AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:pathStr]];
    
    httpClient.parameterEncoding=AFJSONParameterEncoding;
    
    [httpClient registerHTTPOperationClass:[AFJSONRequestOperation class]];
    
    [httpClient setDefaultHeader:@"Accept" value:@"application/json"];
    
    
    
//    NS