RestKit GET请求queryParameter：没有匹配responseDescriptor

我试图用Restkit做一个请求，但我得到以下错误：

{Error Domain=org.restkit.RestKit.ErrorDomain Code=1001 "No mappable object representations were found at the key paths searched." UserInfo={NSLocalizedDescription=No mappable object representations were found at the key paths searched., NSLocalizedFailureReason=The mapping operation was unable to find any nested object representations at the key paths searched: This likely indicates that you have misconfigured the key paths for your mappings., keyPath=null, DetailedErrors=( )}}, keyPath=null, NSLocalizedDescription=No response descriptors match the response loaded.} 

Request-URL是： http : //www.iwi.hs-karlsruhe.de/hskampus-news/api/kampus-api.php?getCategoriesNiceJSON

ResponseDescriptor看起来像：

 let newsCategoryResponseDescriptor = RKResponseDescriptor(mapping: NewsCategory.restKitObjectMapping(), method: RKRequestMethod.GET, pathPattern: Constants.Backend.NewsCategoryResource, keyPath: nil, statusCodes: RKStatusCodeIndexSetForClass(RKStatusCodeClass.Successful)) 

PathPattern：

 hskampus-news/api/kampus-api.php?getCategoriesNiceJSON 

我怎样才能configuration我的ResponseDescripter来匹配我的请求与URL参数？