NSUserDefault can't save & load in Extension in iOS8

Question

I need to save data to NSUserDefault in my iOS Custom Keyboard. I have successfully created App Groups and entitlement in developer portal and XCode.

Here is how i save my value with UISwitch

- (IBAction)switchAction:(id)sender
{
    [self.defaults setBool:self.myKey.on forKey:@"myValue"];

    [self.defaults synchronize];
}

and here is how i load value in KeyboardView.

self.defaults = [[NSUserDefaults alloc] initWithSuiteName:@"group.mycompany.customkeyboard"];

if([self.defaults boolForKey:@"myValue"])
{
    self.backgroundColor = [UIColor redColor];
}

else
{
    self.backgroundColor = [UIColor blackColor];
}

It's doesn't work and doesn't load value.

How can i save and load data?

Answer 1

Initialize your NSUserDefaults object like this in all applications in the app group and they will share the database:

[[NSUserDefaults alloc] initWithSuiteName:@"group identifier"];

Keep in mind everything from the [NSUserDefaults standardUserDefaults] database for each application will not carry over into this database.

The documentation indicates that [NSUserDefaults standardUserDefaults] should return the shared database like the above code does, however it does not. I filed this as a bug (rdar://17164758).

And don't forget to synchronize the database:

[yourDefaults synchronize];

Answer 2

Ok, So I had a look around becuase I had the exact problem. What I did that worked was to add the main app and the extension to a group, Go to main project->Target->Capabilities and create a group (if you don't have one, or make one anyway) like this:

Then, go to the Extension below the target (E), again to Capabilities and add the extension to the group (exactly the same app group as you did for the main target), like this:

Then, once you have done both, in your main app, whenever you want to add something, create a new instance of NSUserDefaults, but for the Suitename equal to the groupname you made earlier. Like this:

NSArray *testing = @[@"first",@"Second",@"Third"];
NSUserDefaults *userd = [[NSUserDefaults alloc]initWithSuiteName:@"The gouprname I made earlier"];//This is exactly the same as the groupname
[userd setObject:testing forKey:@"ExtensionArray"];//set the object you want to share
[userd synchronize]; //It's a good idea to sync, just to be on the safe side.

In your extension's ViewController, use the same group name but to read the user defaults:

NSUserDefaults *sharedD=[[NSUserDefaults alloc]initWithSuiteName:@"Exactly the same groupname that I gave both in the Capabilities and when initialising the userdefault"];
self.testing = [[NSArray alloc]initWithArray:[sharedD arrayForKey:@"ExtensionArray"]];

And Voila! the array is there! I read somewhere that you can even add notification functionality for when the object changes, using a Wormhole class, but I can't find the link to it. I'm sure if you google for Wormhole class, you'll come across it.

I hope I could help, and if you found any more info, please share it with me.