ios - AFHTTPSessionManager posting video swift -

i trying upload video in background using afnetworking > afhttpsessionmanager post method. want conitune uploading if app suspended. error while executing code, logs no error, , points in code. tried every solution available on other posts regarding scenario, couldn't working. plesae check code below , suggest me solution or link me somewhere make work

{     let urlstring = baseurl + weblinks.post      let appid = nsbundle.mainbundle().bundleidentifier      let config = nsurlsessionconfiguration.backgroundsessionconfigurationwithidentifier(appid!)// crashes     //let config = nsurlsessionconfiguration.defaultsessionconfiguration()//doesnt work in background      config.allowscellularaccess = true     config.timeoutintervalforrequest = nstimeinterval(999)     config.timeoutintervalforresource = nstimeinterval(999)      let manager = afhttpsessionmanager(baseurl: nsurl(string: urlstring), sessionconfiguration: config)     manager.responseserializer.acceptablecontenttypes = nsset(object: "application/json") set<nsobject>     manager.requestserializer.setvalue(persistencemanager.sharedinstance.accesstoken, forhttpheaderfield: "authorization")      let param = [         "subject":subject,     ]     print(urlstring)      manager.post(urlstring, parameters: param, constructingbodywithblock: { (formdata) -> void in          if var imagetoupload = image {             imagetoupload = imagetoupload.resizeimage(1200)             let imagedata = uiimagejpegrepresentation(imagetoupload, 0.9);             formdata.appendpartwithfiledata(imagedata, name: "post_image", filename: "picture.jpg", mimetype: "image/jpeg")         }         if let videourl = video {              //let videodata = nsdata(contentsofurl: videourl)             //formdata.appendpartwithfiledata(videodata, name: "post_video", filename: "video.mp4", mimetype: "video/quicktime")             do{                 try formdata.appendpartwithfileurl(videourl, name: "post_video", filename: "video.mp4", mimetype: "video/quicktime")             }catch{                 print("failed attach video")             }         }          }, success: { (nsurlsessiondatatask, response) -> void in             print (response)         }) { (nsurlsessiondatatask, error) -> void in             print (error.localizeddescription)     } }