iOS application: how to clear notifications?

Question

I've an iOS application where some Push Notification are sent to. My problem is, that the messages/notifications stays in the Notification Center in iOS after then are tapped. How can I remove a notification for my application in the Notification Center next time the application opens?

I came across posts where people are calling setApplicationIconBadgeNumber to a zero-value to clear the notifications. That's seems very weird to me, so I believe that maybe another solution exists?

EDIT1:

I'm having some problems clearing the notifications. Please see my code here:

- (void) clearNotifications {
    [[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0];
    [[UIApplication sharedApplication] cancelAllLocalNotifications];
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    if (launchOptions != nil)
    {
        NSDictionary* dictionary = [launchOptions objectForKey:UIApplicationLaunchOptionsRemoteNotificationKey];
        if (dictionary != nil)
        {
            NSLog(@"Launched from push notification: %@", dictionary);

            [self clearNotifications];
        }
    }

    return YES;
}

- (void)application:(UIApplication*)application didReceiveRemoteNotification:(NSDictionary*)userInfo
{    
    NSLog(@"Received notification: %@", userInfo);
    [self clearNotifications];
}

I'm running the App through Xcode. When the App is minimized and I start the App using the notification in the Notification Center, I can see in the log, that the didReceiveRemoteNotification is called and using breakpoints I can see, that the clearNotifications has ran. But still the notification hangs in the Notification Center. Why?

Answer 1

If you're coming here wondering the opposite (as I was), this post may be for you.

I couldn't figure out why my notifications were clearing when I cleared the badge...I manually increment the badge and then want to clear it when the user enters the app. That's no reason to clear out the notification center, though; they may still want to see or act on those notifications.

Negative 1 does the trick, luckily:

[UIApplication sharedApplication].applicationIconBadgeNumber = -1;

Answer 2

Got it from here. It works for iOS 9

UIApplication *app = [UIApplication sharedApplication];
NSArray *eventArray = [app scheduledLocalNotifications];
for (int i=0; i<[eventArray count]; i++)
{
    UILocalNotification* oneEvent = [eventArray objectAtIndex:i];
    //Cancelling local notification
    [app cancelLocalNotification:oneEvent];
}

Answer 3

Just to expand on pcperini's answer. As he mentions you will need to add the following code to your application:didFinishLaunchingWithOptions: method;

[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0];
[[UIApplication sharedApplication] cancelAllLocalNotifications];

You Also need to increment then decrement the badge in your application:didReceiveRemoteNotification: method if you are trying to clear the message from the message centre so that when a user enters you app from pressing a notification the message centre will also clear, ie;

[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 1];
[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0];
[[UIApplication sharedApplication] cancelAllLocalNotifications];

Answer 4

When you logout from your app, at that time you have to use a below line of code on your logout button click method.

[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0];

[[UIApplication sharedApplication] cancelAllLocalNotifications];

and this works perfectly in my app.

Answer 5

Most likely because Notification Center is a relatively new feature, Apple didn't necessarily want to push a whole new paradigm for clearing notifications. So instead, they multi-purposed [[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0]; to clear said notifications. It might seem a bit weird, and Apple might provide a more intuitive way to do this in the future, but for the time being it's the official way.

Myself, I use this snippet:

[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0];
[[UIApplication sharedApplication] cancelAllLocalNotifications];

which never fails to clear all of the app's notifications from Notification Center.

Answer 6

It might also make sense to add a call to clearNotifications in applicationDidBecomeActive so that in case the application is in the background and comes back it will also clear the notifications.

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    [self clearNotifications];
}