Removing Observer on button click

Question

I need to remove Observer Here is my code add Observer

[self.imageCropper addObserver:self 
                   forKeyPath:@"crop" 
                   options:NSKeyValueObservingOptionNew 
                   context:nil];

My question is how can i remove this added observer on button click

Answer 1

I can read about NSKeyValueObserving Protocol Reference

[self.imageCropper removeObserver:self 
                   forKeyPath:@"crop"];