Objective-C: Where to remove observer for NSNotification?

I have an objective C class. In it, I created a init method and set up a NSNotification in it

//Set up NSNotification
[[NSNotificationCenter defaultCenter] addObserver:self 
                                         selector:@selector(getData)
                                             name:@"Answer Submitted"
                                           object:nil];

Where do I set the [[NSNotificationCenter defaultCenter] removeObserver:self] in this class? I know that for a UIViewController, I can add it into the viewDidUnload method So what needs to be done if I just created an objective c Class?