IOS: store an array with NSUserDefault

Question

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

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

and in application didFinishLaunchingWithOption

myArray= [[NSMutableArray alloc] 
          initWithArray:[[NSUserDefaults standardUserDefaults] 
           objectForKey:@"myArray"]];

it's ok for multitasking device, but for not-multitasking device, how can I solve?

Jacob Relkin · Accepted Answer · 2011-09-27 14:32:26Z

10

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"];
    }
}

edited Sep 27, 2011 at 14:32

answered Sep 27, 2011 at 14:26

Jacob Relkin

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1 Comment

user3246173 Over a year ago

As pointed out in another answer, you need to synchronize the defaults after setting the object. [[NSUserDefaults standardUserDefaults] synchronize];

Vincent · Accepted Answer · 2012-11-14 14:38:30Z

7

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

[[NSUserDefaults standardUserDefaults] synchronize];

answered Nov 14, 2012 at 14:38

Vincent

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Comments

fishinear · Accepted Answer · 2011-10-25 12:51:55Z

3

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.

answered Oct 25, 2011 at 12:51

fishinear

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Comments

kv0 · Accepted Answer · 2011-09-27 14:27:30Z

0

Save NSUserDefaults at

- (void)applicationWillTerminate:(UIApplication *)application

answered Sep 27, 2011 at 14:27

kv0

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Comments

Saurabh Passolia · Accepted Answer · 2011-09-27 14:30:59Z

0

set

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

in

applicationWillTerminate

answered Sep 27, 2011 at 14:30

Saurabh Passolia

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Comments

Catalin · Accepted Answer · 2014-09-20 19:43:04Z

0

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

answered Sep 20, 2014 at 19:43

Catalin

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