ios - How to create local notifications?

Question

How can I setup local notifications so that at the time I set, my app generates a notification/alert with a customized message?

Answer 1

Here is sample code for LocalNotification that worked for my project.

Objective-C:

This code block in AppDelegate file :

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    {
        [launchOptions valueForKey:UIApplicationLaunchOptionsLocalNotificationKey];
        // Override point for customization after application launch.
        return YES;
    }

    // This code block is invoked when application is in foreground (active-mode) 
 -(void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification {

        UIAlertView *notificationAlert = [[UIAlertView alloc] initWithTitle:@"Notification"    message:@"This local notification" 
        delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];

        [notificationAlert show];
       // NSLog(@"didReceiveLocalNotification");
    }

This code block in .m file of any ViewController:

-(IBAction)startLocalNotification {  // Bind this method to UIButton action
    NSLog(@"startLocalNotification");

    UILocalNotification *notification = [[UILocalNotification alloc] init];
    notification.fireDate = [NSDate dateWithTimeIntervalSinceNow:7];
    notification.alertBody = @"This is local notification!";
    notification.timeZone = [NSTimeZone defaultTimeZone];
    notification.soundName = UILocalNotificationDefaultSoundName;
    notification.applicationIconBadgeNumber = 10;

    [[UIApplication sharedApplication] scheduleLocalNotification:notification];    
}

The above code display an AlertView after time interval of 7 seconds when pressed on button that binds startLocalNotification If application is in background then it displays BadgeNumber as 10 and with default notification sound.

This code works fine for iOS 7.x and below but for iOS 8 it will prompt following error on console:

Attempting to schedule a local notification with an alert but haven't received permission from the user to display alerts

This means you need register for local notification. This can be achieved using:

if ([UIApplication instancesRespondToSelector:@selector(registerUserNotificationSettings:)]){

    [application registerUserNotificationSettings [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeAlert|UIUserNotificationTypeBadge|UIUserNotificationTypeSound categories:nil]];
}

You can also refer blog for local notification.

Swift:

You AppDelegate.swift file should look like this:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {    
    // Override point for customization after application launch.
    application.registerUserNotificationSettings(UIUserNotificationSettings(forTypes: UIUserNotificationType.Sound | UIUserNotificationType.Badge | UIUserNotificationType.Alert, categories: nil))

    return true
}

The swift file (say ViewController.swift) in which you want to create local notification should contain below code:

//MARK: - Button functions
func buttonIsPressed(sender: UIButton) {
    println("buttonIsPressed function called (UIButton.description())")

    var localNotification = UILocalNotification()
    localNotification.fireDate = NSDate(timeIntervalSinceNow: 3)
    localNotification.alertBody = "This is local notification from Swift 2.0"
    localNotification.timeZone = NSTimeZone.localTimeZone()
    localNotification.repeatInterval = NSCalendarUnit.CalendarUnitMinute
    localNotification.userInfo = ["Important":"Data"];
    localNotification.soundName = UILocalNotificationDefaultSoundName
    localNotification.applicationIconBadgeNumber = 5
    localNotification.category = "Message"

    UIApplication.sharedApplication().scheduleLocalNotification(localNotification)
}


//MARK: - viewDidLoad

class ViewController: UIViewController {

    var objButton : UIButton!
    . . .

    override func viewDidLoad() {
        super.viewDidLoad()

        . . .

        objButton = UIButton.buttonWithType(.Custom) as? UIButton
        objButton.frame = CGRectMake(30, 100, 150, 40)
        objButton.setTitle("Click Me", forState: .Normal)
        objButton.setTitle("Button pressed", forState: .Highlighted)

        objButton.addTarget(self, action: "buttonIsPressed:", forControlEvents: .TouchDown)

        . . .
    }

    . . .
}

The way you use to work with Local Notification in iOS 9 and below is completely different in iOS 10.

Below screen grab from Apple release notes depicts this.

You can refer apple reference document for UserNotification.

Below is code for local notification:

Objective-C:

1. In App-delegate.h file use @import UserNotifications;

2. App-delegate should conform to UNUserNotificationCenterDelegate protocol

3. In didFinishLaunchingOptions use below code:

   UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
   [center requestAuthorizationWithOptions:(UNAuthorizationOptionBadge | UNAuthorizationOptionSound | UNAuthorizationOptionAlert)
          completionHandler:^(BOOL granted, NSError * _Nullable error) {
                 if (!error) {
                     NSLog(@"request authorization succeeded!");
                     [self showAlert];
                 }
   }];
   
   -(void)showAlert {
       UIAlertController *objAlertController = [UIAlertController alertControllerWithTitle:@"Alert" message:@"show an alert!" preferredStyle:UIAlertControllerStyleAlert];
   
       UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"OK"
         style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
           NSLog(@"Ok clicked!");
       }];
   
       [objAlertController addAction:cancelAction];
   
   
       [[[[[UIApplication sharedApplication] windows] objectAtIndex:0] rootViewController] presentViewController:objAlertController animated:YES completion:^{            
       }];
   
   }
   

4. Now create a button in any view controller and in IBAction use below code :

   UNMutableNotificationContent *objNotificationContent = [[UNMutableNotificationContent alloc] init];
   
   objNotificationContent.title = [NSString localizedUserNotificationStringForKey:@“Notification!” arguments:nil];
   
   objNotificationContent.body = [NSString localizedUserNotificationStringForKey:@“This is local notification message!“arguments:nil];
   
   objNotificationContent.sound = [UNNotificationSound defaultSound];
   
   // 4. update application icon badge number
   objNotificationContent.badge = @([[UIApplication sharedApplication] applicationIconBadgeNumber] + 1);
   
   // Deliver the notification in five seconds.
   UNTimeIntervalNotificationTrigger *trigger =  [UNTimeIntervalNotificationTrigger                                             triggerWithTimeInterval:10.f repeats:NO];       
   
   UNNotificationRequest *request = [UNNotificationRequest requestWithIdentifier:@“ten”                                                                            content:objNotificationContent trigger:trigger];
   
   // 3. schedule localNotification
   UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
   
   [center addNotificationRequest:request withCompletionHandler:^(NSError * _Nullable error) {
       if (!error) {
           NSLog(@“Local Notification succeeded“);
       } else {
           NSLog(@“Local Notification failed“);
       }
   }];
   

Swift 3:

1. In AppDelegate.swift file use import UserNotifications
2. Appdelegate should conform to UNUserNotificationCenterDelegate protocol

3. In didFinishLaunchingWithOptions use below code

   // Override point for customization after application launch.
   let center = UNUserNotificationCenter.current()
   center.requestAuthorization(options: [.alert, .sound]) { (granted, error) in
       // Enable or disable features based on authorization.
       if error != nil {
           print("Request authorization failed!")
       } else {
           print("Request authorization succeeded!")
           self.showAlert()
       }
   }
   
   
   func showAlert() {
       let objAlert = UIAlertController(title: "Alert", message: "Request authorization succeeded", preferredStyle: UIAlertControllerStyle.alert)
   
       objAlert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
       //self.presentViewController(objAlert, animated: true, completion: nil)
   
       UIApplication.shared().keyWindow?.rootViewController?.present(objAlert, animated: true, completion: nil)
   }
   

4. Now create a button in any view controller and in IBAction use below code :

   let content = UNMutableNotificationContent()
   content.title = NSString.localizedUserNotificationString(forKey: "Hello!", arguments: nil)
   content.body = NSString.localizedUserNotificationString(forKey: "Hello_message_body", arguments: nil)
   content.sound = UNNotificationSound.default()
   content.categoryIdentifier = "notify-test"
   
   let trigger = UNTimeIntervalNotificationTrigger.init(timeInterval: 5, repeats: false)
   let request = UNNotificationRequest.init(identifier: "notify-test", content: content, trigger: trigger)
   
   let center = UNUserNotificationCenter.current()
   center.add(request)