问题
I have an object which conforms to NSFilePresenter protocol that represents my document-based application document package. When a new file is created inside the package, either programmatically using NSFileManager with proper NSFileCoordination methods or via Finder i only got -presentedSubitemDidChangeAtURL: event, but not seeming so obvious in this case -presentedSubitemDidAppearAtURL:.
Is this an expected behavior or i am doing something wrong?
The comments on -presentedSubitemDidAppearAtURL: in NSFilePresenter state it clear:
Be notified that a file or directory contained by the directory has been added. If this method is not implemented but
-presentedItemDidChangeis, and the directory is actually a file package, then the file coordination machinery will invoke-presentedItemDidChangeinstead.
回答1:
After struggling with this exact issue for quite a while, I opened a technical support issue with Apple. Their response was that this is a bug, and the only thing we can do right now is to do everything through -presentedSubitemDidChangeAtURL:.
I would encourage anyone encountering this issue to file a bug (https://bugreport.apple.com) to encourage Apple to get this problem fixed as soon as possible.
回答2:
https://developer.apple.com/library/mac/documentation/Foundation/Reference/NSFilePresenter_protocol/
Your presenter objects are not notified about changes made directly using low-level read and write calls to the file. Only changes that go through a file coordinator result in notifications.
来源：https://stackoverflow.com/questions/12389726/nsfilepresenter-presentedsubitemdidappearaturl-method-never-gets-called