ios - Rest json POST error Handling in Swift 2 -

an new swift 2 , try write app in swift 2 makes http post request can't figure out how use new error handling of swift 2.am using try catch method still error shows "terminating app due uncaught exception 'nsinvalidargumentexception', reason: '*** +[nsjsonserialization datawithjsonobject:options:error:]: invalid top-level type in json write"

here code works in swift 1.2

//post request json     var request = nsmutableurlrequest(url: nsurl(string: url)!)     var session = nsurlsession.sharedsession()     request.httpmethod = "post"      var jsonstring = "{\"authentication\":{\"username\":\"test\",\"password\":\"test\"},\"requesttype\":4}"     var err: nserror?     request.httpbody = jsonstring.datausingencoding(nsutf8stringencoding, allowlossyconversion: true)     request.addvalue("application/json", forhttpheaderfield: "content-type")     request.addvalue("application/json", forhttpheaderfield: "accept")     var task = session.datataskwithrequest(request, completionhandler: {data, response, error -> void in         //println("response: \(response)")         var strdata = nsstring(data: data!, encoding: nsutf8stringencoding)         print("body: \(strdata)")         var err: nserror?         var json = nsjsonserialization.jsonobjectwithdata(data, options: .mutableleaves, error: &err) as? nsdictionary         // did jsonobjectwithdata constructor return error? if so, log error console         if(err != nil) {             println(err!.localizeddescription)             let jsonstr = nsstring(data: data!, encoding: nsutf8stringencoding)             println("error not parse json: '\(jsonstr)'")             //postcompleted(succeeded: false, msg: "error")         }         else {             // jsonobjectwithdata constructor didn't return error. but, should still             // check , make sure json has value using optional binding.             if let parsejson = json {                 // okay, parsedjson here, let's value 'success' out of                  let success = parsejson["statuscode"]as? int                  if(success == 200) {                     println("success")                 }                 return             }             else {                 //                    // woa, okay json object nil, went worng. maybe server isn't running?                 let jsonstr = nsstring(data: data, encoding: nsutf8stringencoding)                 println("error not parse json: \(jsonstr)")                 self.loadingindicator.stopanimating()             }         }     })     task.resume() 

and trying below code in swift 2

     //post request json         let request = nsmutableurlrequest(url: nsurl(string: url)!)         let session = nsurlsession.sharedsession()         let jsonstring : nsstring = "{\"authentication\":{\"username\":\"\(usernametextfield.text)\",\"password\":\"\(passwordtextfield.text)\"},\"requesttype\":7}"         request.httpmethod = "post"          //request.httpbody = jsonstring.datausingencoding(nsutf8stringencoding, allowlossyconversion: true)         request.addvalue("application/json", forhttpheaderfield: "content-type")         request.addvalue("application/json", forhttpheaderfield: "accept")           {             let param = jsonstring.datausingencoding(nsutf8stringencoding)             request.httpbody = try nsjsonserialization.datawithjsonobject(param!, options: [])         } catch {             print(error)             request.httpbody = nil         }               let task = session.datataskwithrequest(request, completionhandler: {data, response, error -> void in                 // handle error                 guard error == nil                     else                 {                     return                 }                 print("response: \(response)")                 let strdata = nsstring(data: data!, encoding: nsutf8stringencoding)                 print("body: \(strdata)")                 let json: nsdictionary?                 {                     json = try nsjsonserialization.jsonobjectwithdata(data!, options: .mutableleaves) as? nsdictionary                 } catch let dataerror {                     // did jsonobjectwithdata constructor return error? if so, log error console                     print(dataerror)                     let jsonstr = nsstring(data: data!, encoding: nsutf8stringencoding)                     print("error not parse json: '\(jsonstr)'")                     // return or throw?                     return                 }                   // jsonobjectwithdata constructor didn't return error. but, should still                 // check , make sure json has value using optional binding.                 if let parsejson = json {                     // okay, parsedjson here, let's value 'success' out of                     let success = parsejson["success"] as? int                     print("succes: \(success)")                 }                 else {                     // woa, okay json object nil, went worng. maybe server isn't running?                     let jsonstr = nsstring(data: data!, encoding: nsutf8stringencoding)                     print("error not parse json: \(jsonstr)")                 }              })              task.resume() 

let param = jsonstring.datausingencoding(nsutf8stringencoding) request.httpbody = try nsjsonserialization.datawithjsonobject(param!, options: []) 

here you're converting string nsdata , feeding result datawithjsonobject. sincerely doubt that's wanted :)

try instead:

request.httpbody = try nsjsonserialization.datawithjsonobject(jsonstring, options: [])