Detect overwritten file using NSDocument

Question

I have an OSX app which uses NSDocument and autosaves inplace - all works well. Sometimes the user will save the document into a Dropbox synced folder and there is then the chance that the document will be updated (via Dropbox) whilst its still open in the app. Question is, how do I detect this and reload the document from disk (or at least inform the user.)

Thanks

Answer 1

NSDocument implements the NSFilePresenter protocol out of the box. You can override presentedItemDidChange to update automatically when the file has changed.