Timeout error when loading and app enter background


I use MVCS in my app developement. When the data is large and the app in currently loading it and then the app enterbackground by hitting the home button or phonecall. If I return to the app after 5 minute or something ,I always get the “Timeout error” or 'Hostname not found" .

Isn’t NSURLConnection suppose to continue the downloading process for me ? The server that connected to is my own server making to supply JSON return as my request.