php - The data couldn’t be read because it isn’t in the correct format error in Swift 3 -

i'm working on project have access external database in order insert data. i'm using swift 3 , below swift 3 code , php code.

func applybuttonpressedfunction(sender:uibarbuttonitem) {     let urlofsmartcf = url(string: "http://192.168.1.99/insertdata.php")     let request = nsmutableurlrequest(url: urlofsmartcf! url)     request.httpmethod="post"     request.addvalue("application/json", forhttpheaderfield: "accept")     contact in contactscaptuure     {         let usermobilenumber = dbmanager.shared.retriveregisterednumberofmobile()         print(string(describing: usermobilenumber!))         print(contact.phonenumber!)          let postparameters = "{\"usermobilenum\":\(string(describing: usermobilenumber!)),\"contactnum\":\(contact.phonenumber!)}";         print(postparameters)         request.httpbody = postparameters.data(using: string.encoding.utf8)         let task = urlsession.shared.datatask(with: request urlrequest)         {             data, response, error in              if error != nil             {                 print("error \(string(describing: error))")                 return;             }                         {                 let myjson = try jsonserialization.jsonobject(with: data!, options: .mutablecontainers) as? nsdictionary                 if let parsejson = myjson                 {                     var msg : string!                     msg = parsejson["message"] as! string?                     print(msg)                  }             }             catch             {                 print(error.localizeddescription)                 print(error)             }          }         print("done")         task.resume()     }  } 

insertdata.php php code:

<?php  if($_server["request_method"]=="post") {     require 'connectdb.php';     $userphone = $_post["usermobilenum"];     $contactnum = $_post["contactnum"]; // codes } 

however gives me 2 errors when perform function. error[1] error.localization , other came catch.

[1]the data couldn’t read because isn’t in correct format error [2]error domain=nscocoaerrordomain code=3840 "no value." userinfo={nsdebugdescription=no value.} 

what did

since error occurs when emtpy data passed jsonobjectwithdata , php server has sent response empty body far know. checked postparameters string value , evaluated via online page check whether in valid json format , string passed. still couldn't identify problem.

went through lots of web sites , questions hours , came here ask help. appriciate if can give hand here.