ios - Access file with file : // url -

i have created application can upload locally saved files in amazon server

i app have used nsurlsessionuploadtask upload files ,

but in here

@try {       task = [[self backgroundurlsession] uploadtaskwithrequest:request2 fromfile:url];       [task resume];     }     @catch (nsexception *exception) {         nslog(@"exception %@",exception);     } 

i recieve , not valid url file://url exception , checked file url ,

/var/mobile/containers/data/application/7494df09-866a-4088-ac73-710a21a6569a/documents/xxxx/1417516256_event_138_footage_1209_cam_001.mp4

how can change url in file:// type, , meaning of file:// located