IOS: store an array with NSUserDefault

Question

I want to store an array with NSUserDefault, then, I put in applicationDidEnterBackground

[[NSUserDefaults standardUserDefaults] setObj         


        

Answer 1

Save NSUserDefaults at

- (void)applicationWillTerminate:(UIApplication *)application 

Answer 2

Do not forget to sync the buffer before going into background:

[[NSUserDefaults standardUserDefaults] synchronize];

Answer 3

and don't forget to use the encodeWithCoder and initWithCoder inside the object that you are trying to save and that is contained in the array

Answer 4

set

[[NSUserDefaults standardUserDefaults] setObject:myArray forKey:@"myArray"];

in

applicationWillTerminate

Answer 5

Store the object in NSUserDefaults in -applicationWillTerminate:, if it hasn't already been saved by the invocation of -applicationDidEnterBackground: (i.e. check if multitasking is supported, if it is, then don't save it because it's already been saved.)

- (void) applicationWillTerminate:(UIApplication *) app {
    if([[UIDevice currentDevice] respondsToSelector:@selector(isMultitaskingSupported)] &&
       ![[UIDevice currentDevice] isMultitaskingSupported]) {
       [[NSUserDefaults standardUserDefaults] setObject:myArray forKey:@"myArray"];
    }
}

Answer 6

The previous answers are all correct, but note that neither applicationDidEnterBackground nor applicationWillTerminate are guaranteed to be called in all situations. You are usually better off storing important data whenever it has changed.