Event notifications in macOS

Question

Is it possible for a macOS application to listen for specific events originating from another application?

I'd like to detect when Time Machine backups are initiated, in order to create point-in-time snapshots of the NAS folder where the sparsebundle is located.

Answer 1

The Time Machine engine sends distributed notifications.

Add an observer

Objective-C

[[NSDistributedNotificationCenter defaultCenter] addObserver:self
                                                   selector:@selector(handleNotifications:)
                                                       name:nil
                                                     object:nil];

Swift

DistributedNotificationCenter.default().addObserver(self, selector: #selector(handleNotifications), name: nil, object: nil)

and implement the corresponding selector

Objective-C

- (void)handleNotifications:(NSNotification *)notification {
    NSLog(@"%@", notification);
}

Swift

@objc func handleNotifications(_ notification : Notification) {
    print(notification)
}

You have to filter the notifications related to Time Machine. You can also observe specific notifications via the name parameter