DETECTION METHOD FOR CHANGING VALUE OF CLIPBOARD

Unfortunately, for NSPasteboard,

• No change notification
• I don't even have a delegate to communicate the change
• No properties to monitor

So I guess I have no choice but to poll myself (see if there are any changes on a regular basis).

I would like to introduce you to someone who posted the monitoring class code written in Swift on Question of our Stack Overflow home.(I'm just using the NSTimer to periodically check for changes in the NSPasteboard state.)

Swift 2.2 calls the delete method only when a warning code is issued and a file URL with a specific extension is written, but you should study it yourself and rewrite it to suit your needs.(Some of the protocol declarations for delete are missing in the article, but please point to the source of the link.)

It looks like this.

 // Keep the appropriate class (usually AppDelegate or ViewController) compliant with 'PasteboardWatcherDelegate'
class MyClass —PasteboardWatcherDelegate/*, ...*/{
    // Monitoring objects must be retained for the duration you want to monitor
    private var watcher —PasteboardWatcher!

    // In the initialization method
    func myMethod(){
        watcher = PasteboardWatcher (fileKinds: ["png", "jpg")
        // Since circular references are available as they are, the original source, `var delete:PasteboardWatcherDelegate?`, will be used as a reference.
        // `weak vardelegate: PasteboardWatcherDelegate?`
        watcher.delegate=self
    }

    // Implementation of the `PasteboardWatcherDelegate` method
    func newlyCopiedUrlObtained (copiedUrl copiedUrl:NSURL) {
        // This method is called if the file URL string has the specified extension
        print(copiedUrl)
    }
}

I'm sorry, but I haven't tried to see how useful it is.(You may need to make some modifications to the above.) The questions in the article I introduced were written more than 5 years ago, but Apple still doesn't work, so you might not want certain apps to easily monitor and monopolize the content of the clipboard, which is supposed to be shared throughout the system.