Why not use extension to make default implementation for OperationObserver protocol?

[dreamume]

Hey,

Sometimes I use OperationObserver protocol, but I only want to do something in operationDidFinish func. I must also implement the other 3 funcs, too.

If I add bellow extension, I can only implement operationDidFinish function only!

public extension OperationObserver {
    func operationDidStart(operation: Operation) {
    }

    func operationDidCancel(operation: Operation) {
    }

    func operation(operation: Operation, didProduceOperation newOperation: NSOperation) {
    }

    func operationDidFinish(operation: Operation, errors: [NSError]) {
    }
}

So I think It will make OperationObserver protocol more friendly to use.

[mcmurrym]

I would recommend creating a DidFinishOperationObserver implementation of OperationObserver. if you feel it should be added to PSOperations, you should submit a pull request :)