NSUserNotificationCenter dismiss notification

问题:

I'm trying to use the new Mountain Lion NSUserNotificationCenter for my application (which isn't too hard actually). Posting notifications works like a charm via

NSUserNotification *userNotification = [[NSUserNotification alloc] init];
userNotification.title = @"Some title";
userNotification.informativeText = @"Some text";

[[NSUserNotificationCenter defaultUserNotificationCenter] deliverNotification:userNotification];

However, i'd like to dismiss all notifications that are on the screen once the app gains focus. E.g. like the new Messages app does it. When new messages are received in the background, notifications are shown. When the app becomes active again, these are dismissed automatically and vanish from the screen and from the Notification Center.

To replicate this, I've registered a method to the NSApplicationDidBecomeActiveNotification notification which also gets called succesfully. In there I call [NSUserNotificationCenter defaultUserNotificationCenter] removeAllDeliveredNotifications].

This, however, has the effect that notifications that have been collected in the Notification Center are removed while the corresponding "bubbles" that are displayed in the top right corner are still displayed.

Iterating all delivered notifications and removing them each on their own has the exactly same effect, as has using scheduleNotification instead of deliverNotification.

Am I the only one experiencing this, or am I missing something to dismiss the on-screen part and the Notification Center part of a notification programatically?

回答1:

The Messages app is probably using the private NSUserNotificationCenter _removeAllDisplayedNotifications or _removeDisplayedNotification: method.

You can try to use these methods to test if this is what you are looking for. Just add this category interface to declare the methods:

@interface NSUserNotificationCenter (Private)
- (void)_removeAllDisplayedNotifications;
- (void)_removeDisplayedNotification:(NSUserNotification *)notification;
@end

Unfortunately, since these are undocumented methods, you can not use them in an app distributed through the App Store. If this is indeed what you are looking for, then you should file a bug and ask for these methods to become part of the public API.

回答2:

As of 10.9, the following methods remove any displayed notifications:

// Clear a delivered notification from the notification center. If the 
// notification is not in the delivered list, nothing happens.
- (void)removeDeliveredNotification:(NSUserNotification *)notification;

// Clear all delivered notifications for this application from the 
// notification center.
- (void)removeAllDeliveredNotifications;

The behavior seems to have changed since 10.8, as any displayed notifications are removed as well when these methods are called (thanks @0xced for clarification).

回答3:

removeDeliveredNotification is removing the displayed notification for me (on 10.11), the caveat being the identifier on the notification must be set.