UsingNSMetadataQuery.swift

    func perform(query: String) {
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(didUpdate(with:)),
                                               name: Notification.Name.NSMetadataQueryDidUpdate,
                                               object: nil)

        NotificationCenter.default.addObserver(self,
                                               selector: #selector(didFinish(with:)),
                                               name: Notification.Name.NSMetadataQueryDidFinishGathering,
                                               object: nil)
        metadataQuery = NSMetadataQuery()
        metadataQuery.predicate = NSPredicate(format: "kMDItemTextContent like[c] %@", query)

        //NSHomeDirectory() on sandboxed apps is the sandbox itself
        //http://stackoverflow.com/questions/9553390/how-do-i-get-the-users-home-directory-in-objective-c-in-a-sandboxed-app
        metadataQuery.searchScopes = ["/Users/mhlebar"]
        metadataQuery.start()
    }

    func didUpdate(with notification: NSNotification) {
    }

    func didFinish(with notification: NSNotification) {
        for item in metadataQuery.results as! [NSMetadataItem] {
            print(item.value(forAttribute:NSMetadataItemPathKey)!)
        }

        metadataQuery.stop()
    }