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NSOperation *operation = /*some operation*/;
[operationQueue addOperation:operation];
// …
// Some work
// …
return Value;
I want to get Value from function before operation ends.
As far as I know, you can’t.
You may wait for an operation to be done, but trying to preempt a threadpool task is somewhat pointless.
Even if you managed to pause/suspend the queue before you add your
operation, you still have to resume it before youreturn, and you have no way to avoid a possible context switch at this point.If the
Valuebeing returned is a shared var/global/field which might get modified by the operation, you may copy/clone its current value into a tempvar/local before theaddOperationto return it later.