NSNotificationCenter in document-based app

Question

I'm using NSNotificationCenter to send custom notifications in a document-based app.

A document-based app can have many open documents. Ideally, I would like the the document and its children to receive only the notifications created within the document or its children. In other words, a document should receive only the notifications that the same document generates.

At first I thought I could use the notificationSender parameter of addObserver:selector:name:object: but then I realised that I don't always know which object will send the notification.

Do I have to check if I'm in the right document for every custom notification? Is there a better way to do this?

score 3 · Accepted Answer · answered Sep 04 '12 at 18:46

3

I think that your approach works if you use the main document as notificationSender argument for both addObserver:selector:name:object: and postNotificationName:object:.

answered Sep 04 '12 at 18:46

Martin R

529,903
94
1,240
1,382

That's what I first tried. But if I do that I can't send the real sender (some object related to document that generates the notification). – hpique Sep 04 '12 at 20:51
@hpique: Perhaps you can use the `userInfo` parameter to pass the real sender? – Martin R Sep 04 '12 at 21:24

score 2 · Answer 2 · answered Dec 25 '19 at 14:43

You can define a NotificationCenter in your NSDocument class and use that to post notifications within a document (Swift):

class Document: NSDocument {

    let notificationCenter = NotificationCenter()

    // Other stuff
}

And call it like this:

document.notificationCenter.post(name: yourNotificationIdentifier, object: nil)

NSNotificationCenter in document-based app

2 Answers2