NSUserNotificationCenter not showing notifications

Question

I'm not sure if I got something wrong but from the examples I could find. I wrote that little helloworld.

#import <Foundation/Foundation.h>
#import <Foundation/NSUserNotification.h>


int main (int argc, const char * argv[])
{
    NSUserNotification *userNotification = [[NSUserNotification alloc] init];
    userNotification.title = @"Some title";
    userNotification.informativeText = @"Some text";

    [[NSUserNotificationCenter defaultUserNotificationCenter] deliverNotification:userNotification];

    return 0;
}

I compile it with:

cc -framework Foundation -o app main.m

It compiles and I can execute it but it won't show anything. For some reasons, nothing gets presented. I read that Notifications may not get displayed if the application is the main actor. How can I make it show Notification?

score 7 · Answer 1 · edited May 11 '18 at 00:51

7

set a delegate and override

- (BOOL)userNotificationCenter:(NSUserNotificationCenter *)center 
                               shouldPresentNotification:(NSUserNotification *)notification {
  return YES;
}

edited May 11 '18 at 00:51

ocodo

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answered May 06 '13 at 12:06

lxDriver

79
1

could you add a complete sample, i'm not sure to understand where to put that line. – Loïc Faure-Lacroix May 19 '13 at 09:10
1

Great thanks for this. It's interesting that if you do not set the delegate and implement this method, the notification is visible in Notification Center, but does not get displayed. – Ants Jun 26 '13 at 02:48
@Ants how to set delegate in python – imp Nov 18 '13 at 04:42

score 1 · Answer 2 · answered May 11 '18 at 02:14

For a complete example in Objective-C and Swift:

We need to provide a NSUserNotificationCenterDelegate, in the simplest case we can use AppDelegate for this

Objective-C

We need to modify AppDelegate provide NSUserNotificationCenterDelegate method. From a clean AppDelegate (which looks like this...)

@interface AppDelegate ()

We'd modify it to be:

@interface AppDelegate () <NSUserNotificationCenterDelegate>

Now we can provide the required delegate method inside @implementation AppDelegate

- (BOOL)userNotificationCenter:(NSUserNotificationCenter *)center 
                               shouldPresentNotification:(NSUserNotification *)notification {
  return YES;
}

Swift 4

You can use an extension of AppDelegate to provide NSUserNotificationCenterDelegate methods:

extension AppDelegate: NSUserNotificationCenterDelegate {
    func userNotificationCenter(_ center: NSUserNotificationCenter, shouldPresent notification: NSUserNotification) -> Bool {
        return true
    }
}

score 1 · Answer 3 · answered Nov 24 '18 at 00:23

1

Be sure to assign a new identifier for any new notification. A notification will only show once, unless a new identifier is used or the user clears their notification history.

answered Nov 24 '18 at 00:23

Berik

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score 0 · Answer 4 · edited Aug 08 '16 at 08:03

I know it's an old question - but as there may be people looking for an answer how to do this in Python & PyObjC I will post the correct syntax here (as it's one of the top google results). As I can't comment on imp's comment I will post this as another answer.

It's possible to do the same in Python with pyobjc this way:

def userNotificationCenter_shouldPresentNotification_(self, center, notification):
    return True

Full class would look like this:

from Cocoa import NSObject
import objc

class MountainLionNotification(NSObject):
    """ MacOS Notifications """
    # Based on http://stackoverflow.com/questions/12202983/working-with-mountain-lions-notification-center-using-pyobjc

    def userNotificationCenter_shouldPresentNotification_(self, center, notification):
        return True

    def init(self):

        self = super(MountainLionNotification, self).init()
        if self is None: return None

        # Get objc references to the classes we need.
        self.NSUserNotification = objc.lookUpClass('NSUserNotification')
        self.NSUserNotificationCenter = objc.lookUpClass('NSUserNotificationCenter')

        return self

    def clearNotifications(self):
        """Clear any displayed alerts we have posted. Requires Mavericks."""

        NSUserNotificationCenter = objc.lookUpClass('NSUserNotificationCenter')
        NSUserNotificationCenter.defaultUserNotificationCenter().removeAllDeliveredNotifications()

    def notify(self, title="", subtitle="", text="", url=""):
        """Create a user notification and display it."""

        notification = self.NSUserNotification.alloc().init()
        notification.setTitle_(str(title))
        notification.setSubtitle_(str(subtitle))
        notification.setInformativeText_(str(text))
        # notification.setSoundName_("NSUserNotificationDefaultSoundName")
        notification.setHasActionButton_(False)
        notification.setActionButtonTitle_("View")
        # notification.setUserInfo_({"action":"open_url", "value": url})

        self.NSUserNotificationCenter.defaultUserNotificationCenter().setDelegate_(self)
        self.NSUserNotificationCenter.defaultUserNotificationCenter().scheduleNotification_(notification)

        # Note that the notification center saves a *copy* of our object.
        return notification

score 0 · Answer 5 · answered Oct 26 '22 at 02:15

I followed the code on here but was unable to get a notification to work. It turned out that because I was on multiple monitors I needed to check the "When mirroring or sharing the display" option to get the alerts to present themselves. After that the python code worked.

NSUserNotificationCenter not showing notifications

5 Answers5

Objective-C

Swift 4

Linked