Passing data received from a push notification from the AppDelegate to a ViewController

Question

In my app, there's a collection view displaying a set of images retrieved from a web service. Each image has tags. So the app has the ability to filter images using tags as well.

Now I'm trying to add push notifications to this app. A push notification is sent when new images have been added to the server. These images are tagged say, latest. I'm passing that tag as the message via a push notification and what I need is when the user taps on the push notification to open the app, it should load the latest new images to the collection view.

I'm half way done. I receive the push notification with the message successfully to the didReceiveRemoteNotification method in the AppDelegate.m file. Now I need to pass it on to the view controller where the collection view is. I'm stuck at this point. I can't figure out how to send it over to the view controller.

I tried declaring a property in the App delegate, assign the message value to it and referring it from the view controller but it didn't work. I tied delegates, notification center, user defaults but nothing worked.

Can anyone please tell me how to accomplish this?

Thank you.

Edit:

Here's my code. The last method I tried was the local notifications.

AppDelegate.m

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"PushNotificationMessageReceivedNotification" object:nil userInfo:userInfo];
}

ViewController.m

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(remoteNotificationReceived:) name:@"PushNotificationMessageReceivedNotification"
                                               object:nil];
}

- (void)remoteNotificationReceived:(NSNotification *)notification
{
    NSLog(@"Notification: %@", notification.userInfo);
    NSString *msg = [[notification.userInfo valueForKey:@"aps"] valueForKey:@"alert"];
    self.label.text = msg;
}

Answer 1

Case 1: if your app is background and user launches app with notification click then you have the check if app launched form notification or normal

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];


        NSDictionary *remoteNotificationPayload = [launchOptions objectForKey:UIApplicationLaunchOptionsRemoteNotificationKey];
        if (remoteNotificationPayload) {
            [[NSNotificationCenter defaultCenter] postNotificationName:@"notification" object:nil userInfo:remoteNotificationPayload];
       }
return YES; }

Case2: If your app is in forground notification will be received in didReceiveRemoteNotification

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {


    NSLog(@"userinfo %@",userInfo);

    [[NSNotificationCenter defaultCenter] postNotificationName:@"notification" object:nil userInfo:userInfo];
}

Now you and add a observer in any controller with Local notification and do what you wand to do