I would like to register my iOS 4 app as an observer for ALAssetsLibraryChangedNotification and receive notifications when changes happen to the camera roll and photo library. The most obvious scenario is: 1) My app enumerates photo contents using ALAssetsLibrary. 2) Leave my app (goes into background) and launch the camera app. 3) Take a picture. 4) Leave the camera app and return to my app.
I was hoping the ALAssetsLibraryChangedNotification would be delivered when my app returned to the foreground, but this does not seem to be the case. I ve tried both the block and selector form of addObserver. How can I receive notifications when photos are added or removed while my app is in the background?