NSUserNotification not showing action button

magic command based on PARTISAN's reply is:

notification.set_showsButtons_(True)

cha-ching :)

And here was the answer.

Thanks again to #macdev on freenode.

The selection needs to be "Alerts" to have buttons.

As already stated in a previous answer, the notification type needs to be set to alert for the action button to be shown. If you want to set the default notification style of your app to alert, you need to define the key NSUserNotificationAlertStyle in info.plist with the value alert.

See Apple's info.plist keys reference for more details:

NSUserNotificationAlertStyle Specifies whether the notification style should be banners, alerts, or none. The default value is banners, which is the recommended style.

As a contrary instance for other answers we can use iTunes - it still showing "Skip" button even when we setup alert style to banners. So I continued searching and found this github repo where Indragie Karunaratne provide some useful additional properties in NSUserNotification private headers. You can check for full list of the properties in the NSUserNotification_Private.h file, but actual for showing buttons in banner notification style is

@property BOOL _showsButtons; // @dynamic _showsButtons;

so you can just add this line to you code

[notification setValue:@YES forKey:@"_showsButtons"];

and your notification action button will become independent on alert style.