when to use “willChangeValueForKey” and “didChangeValueForKey”?

Question

I saw these lines in a demo project, but I couldn\'t understand why it did that.

[self willChangeValueForKey:@\"names\"];
[self didChangeValueForKey:@\"names\"];         


        

Answer 1

Be really careful when overriding didChangeValueForKey:. The best thing is not to do it at all. But if you do, make sure you call super, otherwise you will have a memory leak as demonstrated here: https://github.com/jfahrenkrug/KVOMemoryLeak