how to implement "show recents" item on OS 10.9 and later - macos

Question

I notice on Mac, every app on docker, when it's not opened and ctrl click it, there will be a pop-up menu, inside has a menu item called "show recents", when open the app this item will become "show all windows". I want to know how to make it work cuz right now, when I click it on my own app, it has nothing to show.
I have tested using doc controller and use noteNewRecentDocumentURL: method, but still, both "open recent" item in "file" and "show recents" in docker, it doesn't show my url I just added.

Answer 1

I do not know, where you click on the app to show the menu. The recent documents list is shown
in the app's File menu in the submenu Open Recent
in the dock menu for the app as a list with one item per document
likely at some other places related to the app
However where it is shown, the list is automatically managed by [NSDocumentController sharedDocumentController], which is added to the project template for document-based applications. If you do not have a document-based application you should re-check, whether this would be the better choice. But you can use [NSDocumentController sharedDocumentController] in a non-document-based application as well:
In some situations, it is worthwhile to subclass NSDocumentController in non-NSDocument-based applications to get some of its features. For example, the NSDocumentController management of the Open Recent menu is useful in applications that don’t use subclasses of NSDocument.
Documentation
There is a section Managing the Open Recent Menu containing the description of the method -noteNewRecentDocumentURL: in the documentation of NSDocumentController. You have to send this message to the shared instance,
whenever you want to add an item to the recent docs list:
[[NSDocumentController sharedDocumentController] noteNewRecentDocumentURL:theURLOfTheDocYourAppOpens];
Please note:
Applications not based on NSDocument must also implement the application:openFile: method in the application delegate to handle requests from the Open Recent menu command.
If you do not want to use the document controller, you have to maintain the list yourself and add it to the different locations manually. You can start here. I do not recommend that.

Answer 2

Here's code for use with Xamarin.Mac.
// Add the file to the menu. Note creation of file url.
void AddFileToOpenRecentMenu(string filePath)
{
var fileUrl = NSUrl.FromFilename(filePath);
NSDocumentController.SharedDocumentController.NoteNewRecentDocumentURL(fileUrl);
}
// Open the file selected from the menu (in AppDelegate.cs)
[Export("application:openFile:")]
public override bool OpenFile(NSApplication sender, string filename)
{
var keepFileInMenu = ProcessFile(filename);
return keepFileInMenu;
}