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 · 2011-09-27T14:32:26.760

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 '11 at 14:32

answered Sep 27 '11 at 14:26

Jacob Relkin

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As pointed out in another answer, you need to synchronize the defaults after setting the object. [[NSUserDefaults standardUserDefaults] synchronize]; – user3246173 Sep 19 '15 at 18:28

score 7 · Answer 2 · answered Nov 14 '12 at 14:38

7

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

[[NSUserDefaults standardUserDefaults] synchronize];

answered Nov 14 '12 at 14:38

Vincent

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score 3 · Answer 3 · answered Oct 25 '11 at 12:51

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 '11 at 12:51

fishinear

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score 0 · Answer 4 · answered Sep 20 '14 at 19:43

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 '14 at 19:43

Catalin

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score 0 · Answer 5 · answered Sep 27 '11 at 14:27

0

Save NSUserDefaults at

- (void)applicationWillTerminate:(UIApplication *)application

answered Sep 27 '11 at 14:27

kv0

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score 0 · Answer 6 · answered Sep 27 '11 at 14:30

0

set

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

in

applicationWillTerminate

answered Sep 27 '11 at 14:30

Saurabh Passolia

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IOS: store an array with NSUserDefault

6 Answers6

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