Question

How can I tell the time from the last time my app was open? Can this still be monitored even my app is not running in the background?

Thanks.

Answer 1

Put something like

[[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"kLastCloseDate"];

in both

- (void)applicationWillTerminate:(UIApplication *)application
- (void)applicationDidEnterBackground:(UIApplication *)application

Then check the difference at startup:

NSDate *lastDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"kLastCloseDate"];
NSTimeInterval timeDiff = [[NSDate date] timeIntervalSinceDate:lastDate];
// your stuff

in both

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
- (void)applicationWillEnterForeground:(UIApplication *)application