How to get an update NSUserDefault on iOS 4?

Question

I am developing an iPhone application, I encounter a problem on the iOS4 because of multi task.

This application has the default settings defined in a Settings.bundle. I

Answer 1

You need to listen for settings changes. Best way to do it is to set up a listener wherever you need it:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(settingsChanged) name:NSUserDefaultsDidChangeNotification object:nil];

The only thing you need to make sure of is that you don't change any settings in your listener, or you get infinite recursion without a little more logic being added in.

I'd stay away from synchronizing because in my experience I found I had to run it twice. But that's accidental behavior. A listener will notify you when the new settings have been re-read from the store.

Answer 2

I had the same problem as you, and got around it by calling

[[NSUserDefaults standardUserDefaults] synchronize];

in applicationDidBecomeActive.

For some reason the [NSUserDefaults standardUserDefaults] object you can access in your app isn't synchronized with the actual plist files backing it when an app becomes active again after having been suspended. Calling the synchronize method forces a synchronization.