how to get previous view when entered in foreground in ios -

i've chat view,i'm chating , when enter in background,and once again enter in foreground message have been removed(refresh),how can got same chat message.

- (void)applicationwillenterforeground:(uiapplication *)application {     // called part of transition background inactive state; here can undo many of changes made on entering background.     [[uiapplication sharedapplication] cancelalllocalnotifications];     application.applicationiconbadgenumber = 0;     self.window = [[uiwindow alloc] initwithframe:[[uiscreen mainscreen] bounds]];       sphviewcontroller *chatview = [[sphviewcontroller alloc] initwithnibname:@"sphviewcontroller" bundle:nil];     chatview.strcallername = [nsstring stringwithformat:@"%@",strselectedcallername];     self.window.rootviewcontroller = chatview;     [self.window makekeyandvisible]; } 

you resetting app state every time app enters foreground. that's not place instantiate view controller , set app's main window. need in applicationdidfinishlaunching: