     /*
      便捷的请求方法.
      */
-    public static func wt_dataTask(with url:String, method:httpMethod? = .GET,parameters:[String:String]?=[:],headers: [String: String]? = [:] ,credential:URLCredential?=nil,completionHandler:(Data?, URLResponse?, NSError?) -> Void)->WTURLSessionTask{
+    public static func wt_dataTask(with url:String, method:httpMethod? = .GET,parameters:[String:String]?=[:],headers: [String: String]? = [:] ,credential:URLCredential?=nil,completionHandler:completionHandler)->WTURLSessionTask{
         let request = URLRequest.wt_request(with: url, method: method, parameters: parameters, headers: headers)
         return self.wt_dataTask(with: request,credential:credential, completionHandler: completionHandler)
     }

    }
    
    
    public static func wt_cachedDataTask(with request:URLRequest ,credential:URLCredential?=nil, completionHandler:(Data?, URLResponse?, NSError?) -> Void)->WTURLSessionTask{
        
        
        //        let configuration = URLSessionConfiguration.default

        return myTask
    }
    
    public static func wt_uploadTask(with request:URLRequest,from bodyData:Data,credential:URLCredential?=nil,completionHandler:completionHandler)->WTURLSessionTask{
        let session = self.wt_sharedInstance()
        let task = session.uploadTask(with: request, from: bodyData)
        let myTask = WTURLSessionTask(task: task)
