NSoperation and key value observing?

I havent enough reputation to comment or down-vote but I would down-vote dannywartnaby's answer. NSOperation uses KVO intrinsically in it's operation; having to implement isFinished and isExecuted as part of the processing, for example are 100% KVO and are part of an operation's required contract with a client/queue. So advising that these should be avoided is inaccurate; NSOperation uses KVO itself so adopting dannywartnaby's premise would indicate that the implementation of NSOperation is in itself flawed, which is definitely not the case.

I don't know your use-case, but using KVO for threads/operations isn't wise.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.