On which ViewController should I implement FacebookSDK's removeObserver?
I am implementing facebook's SDK for iOS into my app. There are two functions however that are supposed to register and unregister for the notifications:
From Facebook's login to facebook with ios:
in the viewDidLoad method, register for the session change notification you defined in the app delegate by adding this code to the end of the method:
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:@selector(sessionStateChanged:)
name:FBSessionStateChangedNotification
object:nil];
and
Unregister for the notifications by adding the following code to the end of the didReceiveMemoryWarning the method:
[[NSNotificationCenter defaultCenter] removeObserver:self];
Since I have quite a few view controllers and all of them should be using facebook's API, I thought I should implement the register/unregister methods in the applicationDidFinishLoadingWithOptions (for register for notifications)
but I am not sure if and how I should implement the unregister 's removeObserver command, because applicationDidReceiveMemoryWarning is not available for the AppDelegate.
The application delegate does receive memory warnings:
http://developer.apple.com/library/ios/#documentation/uikit/reference/UIApplicationDelegate_Protocol/Reference/Reference.html
If it didn't, another option would be to use the notification center:
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center addObserver:self
selector:@selector(whatever:)
name:UIApplicationDidReceiveMemoryWarningNotification
object:nil];
That all said, it seems to me that removing the observer on a memory warning is inappropriate. At what point will your reinstate it? But hey, if that's what Facebook recommends...
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