Returns the URL to the default app that would be used to open the given URL.
- macOS 10.6+
The URL of the file to open.
The URL of the default app that would open the specified
url. Returns nil if no app is able to open the url, or if the file url does not exist.
This is the programmatic equivalent of double clicking a document in the Finder.
It is safe to call this method from any thread of your app.