Even if you never want to make an app for the Apple Watch, there’s one place you might want to think about supporting: Notifications. In a previous lesson, we explored how to make local notifications for iOS devices. That lesson ended with a free bonus: If a phone is sleeping and you have an Apple Watch, the notification will go to the watch.
Starting in iOS8, notifications get one big change: they can have actions of their own. On phone, tablet or watch this gives you more flexibility in how to respond to a notification. Suppose you had an app that after an appointment comes up, nags you about it every ten seconds until you stop the nagging. You could of course go into the app and shut it off, but it might be easier to have a stop nagging button on the notification. In this lesson, we’ll make that stop nagging button first for iOS devices, then for the Apple Watch. Along the way we’ll discover why watch notifications are the one place iOS developers should seriously think about for their phone apps.
Making a Demo Program – A Review of Notifications
In a previous lesson we went into detail about local notifications. We’ll be using a lot of what was learned there. In this tutorial, we’ll build a simple app to make a series of notifications similar to the HIIT app at the end of that lesson. We’ll use this as a review and quick introduction to local notifications if you are not familiar with them.
Since we will eventually get to some watch related notifications, make a new project using the iOS with Watch OS App template.
Name the project PhoneWatchNotificationDemo and make sure watch notifications is checked on and everything else is off.
Once you save the project, add a new file by pressing Command-N called NaggyNotification subclassing NSObject. Add these properties to the class
class NaggyNotification: NSObject {
private let basicNags = ["Nag", "Nag nag","Naggity nag"]
private let emojiNags = ["😀","😉","🙄","😒","😠","😡"]
private var nags = ["Nag", "Nag nag","Naggity nag"]
private var counter = 0
private var timer = NSTimer()
private var backgroundTask = 0
private var localNotification = UILocalNotification()
var nagging:Bool {return timer.valid } //read only
}
If you don’t know how to type emojis, press Control-Command-Spacebar to get the symbols palette.
We are going to do something insane a little later with this class. To protect against some of the problems with that, all but one of our properties is private and inaccessible outside the class. There is one read-only property nagging which uses a computed read-only value.
Most of these properties we’ll get to. We’ll start with the most important. The localNotification will contain our notification. Add the following method to present it immediately:
func presentNotificationNow(){
UIApplication.sharedApplication().presentLocalNotificationNow(localNotification)
}
There are two ways to present notifications. We can present immediately as we do with the presentLocalNotificationNow method above or at some scheduled time in the future with the scheduleLocalNotification method. We could schedule that time using the fireDate property of UILocalNotification, but that presents a problem. We can only schedule 64 notifications, which in a nagging app might be too little space. We will take a different approach: Use a NSTimer loop in the background. Add the following method to start a timer:
func startTimer(timeInterval:NSTimeInterval){
if !timer.valid{ //prevent more than one timer on the thread
counter = 0
backgroundTask = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler(nil)
timer = NSTimer.scheduledTimerWithTimeInterval(
timeInterval,
target: self,
selector: #selector(timerDidFire),
userInfo: nil,
repeats: true)
}
}
We do three things in this code. We reset a counter for counting how many nags the user has been subjected to, then set this task into the background. While on a simulator you can leave things in the background without this, your app will suspend operation without beginBackgroundTaskWithExpirationHandler on a live device. Finally we start a timing loop, getting the timing interval from the parameter timeInterval. The timing loop ends on a selector timerDidFire. Let’s add the code for timerDidfire. Add this to the class:
func timerDidFire(timer:NSTimer){
counter += 1
let currentNag = counter % nags.count //cycle through messages
let nagString = String(format:"# %i %@",counter,nags[currentNag])
localNotification.alertBody = nagString
localNotification.alertTitle = "Naggy Notification"
localNotification.category = "Nags"
localNotification.soundName = UILocalNotificationDefaultSoundName
localNotification.userInfo = ["NagNum":counter,"NagString":nags[currentNag]]
presentNotificationNow()
}
If you are not familiar with timing loops you might want to refer to this lesson. Basically, the timer object is set to run the timerDidFire function every timeInterval seconds. Once in the timerDidFire function, we increment counter and compose a string we’ll post to the notification. The property alertBody of UILocalNotification sets the text for the notification. We also set the sound to the default sound, which will also set off vibrations and haptics. For later use, we all send a dictionary containing our count and our current nag as userInfo we can use later in this lesson. Finally we present the notification.
We’ll also need a way to shut down the timer. Add this method to your code:
func stopTimer(){
timer.invalidate()
UIApplication.sharedApplication().endBackgroundTask(backgroundTask)
}
We shut down the timer and remove the task from the background.
Now for the small, but insane bit of code. Add this above the class declaration:
let naggingNotification = NaggyNotification()
class NaggyNotification: NSObject {
...
A variable declared outside a class is global. Global values or instances can be used anywhere in the target code. There are other, better ways of handling the NaggyNotification class, but I could write full tutorials on them. As we’ll see, this instance will show up in several classes. This is a simple way to get it into all of them. As I always do when I use a global, I warn people not to use globals except in special circumstances. They are notoriously hard to track down in code. It’s why I made all the properties private, only methods are accessible to other classes, which are easier to deal with.
In order to use a notification, you must tell the application you will be using the notification in the AppDelegate.swift file. Go to the AppDelegate class Change the application:didFinishLaunchingWithOptions:launchOptions: method to this:
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
// Override point for customization after application launch.
application.registerUserNotificationSettings(
UIUserNotificationSettings(
forTypes:[.Alert, .Sound],
categories: nil
)
)
return true
}
We register the notification settings for the two types of notifications: Alerts(or banners) and sounds(or haptics and vibrations).
Our app has all the internal parts set, we need a user interface. We’ll make a very simple one of a single button. Go to the ViewController.swift file. Change ViewController to this:
class ViewController: UIViewController {
@IBOutlet weak var nagButton: UIButton!
@IBAction func nagButton(sender: UIButton) {
}
}
We’ll have one button that we’ll assign a outlet and action to. Change the nagButton action to this:
@IBAction func nagButton(sender: UIButton) {
if naggingNotification.nagging{
naggingNotification.stopTimer()
}else{
naggingNotification.startTimer(10.0)
}
stateDidChange()
}
This code uses the naggingNotification read-only property nagging to determine if the timer is on. We toggle the timer depending on the result, using the naggingNotification methods stopTimer and startTimer. We’ve set up this demo with a 10 second timer.
Our last statement calls a method we have yet to define stateDidChange(). We’ll update the button title with this. Add this code to ViewController:
func stateDidChange(){
if !naggingNotification.nagging{
nagButton.setTitle"Nag", forState: .Normal)
}else{
nagButton.setTitle("Stop Nagging", forState: .Normal)
}
}
We have our code. Go to the storyboard. Drag one button to the center of the storyboard. Title it Nag, and set the font to 46 point Bradley Hand.
In the lower right corner of the storyboard, you will find the auto layout controls. With the Nag button selected, click the align 
icon to get the align menu. Towards the bottom of this menu you will find the center Horizontally in Container and Vertically in container settings. Click both on with values of zero. Set the Update frames to Items of New constraints.
Open the assistant editor. Drag from both circles in the code to the button to connect the action and the outlet to the button. Close the assistant editor.
Before we test this, launch both the iPhone and watch simulators. If you have never launched these before running an app, check the directions here Especially with the watch, it helps to have them running before you run an app on them.
Build and run using a iPhone 6s plus simulator. You get the notification message the first time you run this:
Press OK to allow notifications.You get a simple screen of a single button:
Tap the Nag button.
The button toggles but doesn’t do more than that. we need to be outside the app to see a notification.
Press Command-Shift-H or on the hardware simulator menu, Hardware>Home. Wait a few seconds and you will see this:
Swipe down from the status bar once the banner disappears. Select Notifications and you will see the notifications appear.
Tap one of the notifications and you are back in the app. Tap Stop Nagging and the notifications turn off.
Adding Categories and Actions to your Notifications
Introduced in iOS8, Notifications now have their own actions, which appear as buttons on a notification. Often you’ll find these in the AppDelegate. I’ll however keep everything on one class for the notification. Actions are of class UIUserNotificationAction and it’s subclass UIMutableUserNotificationAction. Since you can’t change anything in a UIUserNotificationAction, we define actions in UIMutableUserNotificationActions. We’ll define two actions, one to stop the timer and one to change the nag message to emoji. In the NaggyNotification class add the following method:
func makeActions()-> [UIMutableUserNotificationAction]{
let stopAction = UIMutableUserNotificationAction()
stopAction.title = "Stop"
stopAction.identifier = "StopAction"
stopAction.destructive = true
stopAction.authenticationRequired = true
stopAction.activationMode = .Foreground
let moreAction = UIMutableUserNotificationAction()
moreAction.title = "Emoji"
moreAction.identifier = "EmojiAction"
moreAction.destructive = false
moreAction.authenticationRequired = false
moreAction.activationMode = .Background
return [stopAction,moreAction]
}
The title parameter is the title that will appears on buttons of the notification. The identifier is the string used to internally identify the action. You’ll notice that there is no code here to execute the action. We’ll use that identifier to code the action in AppDelegate. We can add a red warning to a button if it is a destructive button, one that deletes something. I used it here as the Stop button, but left destructive as false for the Emoji button. The activationMode has two choices: .Foreground or .Background and indicates if the app will execute the action in the foreground or the background. To maintain security of the user’s phone we can also require an authentication before we execute the action. For actions in the foreground, this is mandatory and activationMode is always true. The statement in our code is redundant.
We return an array of the actions. We will use these actions in a category. Categories contain all information about a specific type of notification. Our category, which we’ll call Nags contains the actions that will show in the nag notification. Add the following code to the NaggyNotification class.
//MARK: - Categories and Actions
func makeCategory()-> UIMutableUserNotificationCategory {
let category = UIMutableUserNotificationCategory()
category.identifier = "Nags"
category.setActions(makeActions(), forContext: .Default)
return category
}
We make set two properties on a UIMutableUserNotificationCategory. We set an identifier Nags and using the setActions:forContext: method add the actions to the category.
We’ve set up our category and actions. Now to use them. We’ll do that in AppDelegate. Find the method we changed earlier. Change the highlighted lines to add the category to our current code.
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) ->; Bool {
// Override point for customization after application launch.
let category = naggingNotification.makeCategory()
application.registerUserNotificationSettings(
UIUserNotificationSettings(
forTypes:[.Alert, .Sound, .Badge],
categories: [category]
)
)
return true
}
If we ran our code now, we would have our actions listed in the notification, but nothing would happen. We need to add a callback method to AppDelegate containing the code to execute the actions. Add this to AppDelegate
func application(application: UIApplication, handleActionWithIdentifier identifier: String?, forLocalNotification notification: UILocalNotification, completionHandler: () -> Void) {
if notification.category == "Nags"{
if identifier == "StopAction"{
naggingNotification.stopTimer()
}
if identifier == "EmojiAction"{
naggingNotification.toggleAlertMessages()
}
}
completionHandler()
}
The application:handleActionWithIdentifier:forlocalNotification method has a actionIdentifier and a UILocalNotification. for parameters.  The code checks the notification’s title. If it is our notification, we check the action identifier and perform the action we need.
We need one more method back in NaggyNotification to toggle the alert messages. Add this to the code.
func toggleAlertMessages(){
if nags == basicNags {
nags = emojiNags
} else {
nags = basicNags
}
}
Fixing a Bug Before It Happens
This is all the code we need to run our application. However, there’s one bug that we’ll fix first. The problem is the Stop action when we are in the background. It will stop the the timer and shut down the nags. The button on our view controller does not know this. With the code as it is written the button still says Stop Nagging when we enter the foreground. We need to update the button any time we do enter the foreground. Find the applicationDidBecomeActive in AppDelegate. This method runs when we need to do that refresh of our user interface. Change it to this
func applicationDidBecomeActive(application: UIApplication) {
let rvc = window?.rootViewController as! ViewController
rvc.stateDidChange() //Update the button
}
Line 2 of the code gets the view controller. We have the view controller as our root view controller, so it’s easy to access. Once we have a reference to the root controller, we can call its method. statDidChange which checks the status of the timer and changes the title to the correct one.
Build and run.
Press the nag button. Press Command-Shift-H. Eventually the notification appears:
Drag the small oval at the bottom of the notification down.
The actions appear.
Tap the emoji button. The next notification you get is an emoji.
Drag down from the status bar and get the notifications. Swipe right to left on one of the notifications.
Tap the Stop button. The app stops and opens up to the Nag screen again.
The Apple Watch for All Developers
While that’s what you need to know for iOS, it’s not the whole story. Unless notifications are turned off by the user of an Apple watch, the watch will receive the notification if the phone is asleep. Sadly, the watch simulator does not always reflect what happens on the watch. You can try using the simulator if you don’t have a watch handy, I’ll be using both since they have slightly different behaviors.
If your app is still running, get the watch and phone simulator visible
Start nagging with the phone, then press Command-L to Lock the phone. The simulator goes black. Wait a few seconds, And you will see the Short-Look Notification appear:
A second later, the Long-Look notification appears.
You’ll notice the buttons for the actions don’t quite fit on the watch. scroll up and you’ll find one more button.
Test the emoji button. Tap it, and the next notification changes to this:
Press the stop button and you get a blank screen with the time. Actually, you are running a blank watch app.
 You get slightly different results with a real phone. Running the app on my phone, I start nagging by pressing the Nag button. I then lock my phone by pressing the switch. SInce I turned on sounds and used the system sound in my actions, I’ll get a Haptic vibration on my wrist, and then the notification.
The notification includes the Emoji button and a dismiss button, which is cut off. You can scroll up to get the rest of the dismiss button. On the simulator, we had the stop button, but on the watch it’s missing.
The difference has to do with activationMode. If you have an action with an activationMode of .Foreground the watch does not display it automatically. The foreground mode on the watch starts the watch app associated with this notification. In the simulator it lets us run that blank app, but on a physical watch it knows there is no app and doesn’t show the button. On the other hand, an activationMode of .Background on the watch sends to the background of the phone. That’s why with no coding, the Emoji button works perfectly. Go to the NaggyNotification class. In makeActions, change our code to put the Stop button in the background
stopAction.activationMode = .Background
Now run the app again and when we lock the phone we get both buttons on the watch:
With more buttons, the dismiss button is missing. Drag up and you will find it:
Tap the Emoji Button. The next notification changes to emoji
Tap the Stop button. On both the live watch and the simulator, the timer stops. All of our actions work on the watch without a single new line of code.
Notifications will happen on an Apple Watch even if you don’t program for it. For Apple watch developer, this provides one way to launch your watch app. For iOS developers using notifications and actions, it means you have one more thing to think about when writing an app. Think out what you want to show and not to show for a watch user. If you are not writing a watch app, you can exclude actions from the watch but not the phone by making the activationMode go to the foreground.
The whole code
NaggyNotification.swift
//
// NaggyNotification.swift
// PhoneWatchNotificationDemo
//
// Created by Steven Lipton on 5/1/16.
// Copyright © 2016 MakeAppPie.Com. All rights reserved.
//
import UIKit
//Global variable -- not always a good idea,
// but makes running this code much simpler
//
let naggingNotification = NaggyNotification()
class NaggyNotification: NSObject {
//All properties are private or read only
//Good insurance for using the global instance
//nothing gets messed up.
private let basicNags = ["Nag", "Nag nag","Naggity nag"]
private let emojiNags = ["😀","😉","🙄","😒","😠","😡"]
private var nags = ["Nag", "Nag nag","Naggity nag"]
private var counter = 0
private var timer = NSTimer()
private var backgroundTask = 0
private var localNotification = UILocalNotification()
var nagging:Bool {return timer.valid } //read only
func presentNotificationNow(){
UIApplication.sharedApplication().presentLocalNotificationNow(localNotification)
}
func toggleAlertMessages(){
if nags == basicNags {
nags = emojiNags
} else {
nags = basicNags
}
}
func startTimer(timeInterval:NSTimeInterval){
if !timer.valid{ //prevent more than one timer on the thread
counter = 0
backgroundTask = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler(nil)
timer = NSTimer.scheduledTimerWithTimeInterval(
timeInterval,
target: self,
selector: #selector(timerDidFire),
userInfo: nil,
repeats: true)
}
}
func timerDidFire(timer:NSTimer){
counter += 1
let currentNag = counter % nags.count //cycle through messages
let nagString = String(format:"# %i %@",counter,nags[currentNag])
localNotification.alertBody = nagString
localNotification.alertTitle = "Naggy Notification"
localNotification.category = "Nags"
//localNotification.alertTitle = localNotification.category
localNotification.soundName = UILocalNotificationDefaultSoundName
localNotification.userInfo = ["NagNum":counter,"NagString":nags[currentNag]]
presentNotificationNow()
}
func stopTimer(){
timer.invalidate()
UIApplication.sharedApplication().endBackgroundTask(backgroundTask)
}
//MARK: - Actions and Categories
func makeActions()-> [UIMutableUserNotificationAction]{
let stopAction = UIMutableUserNotificationAction()
stopAction.title = "Stop"
stopAction.identifier = "StopAction"
stopAction.destructive = true
stopAction.authenticationRequired = true
stopAction.activationMode = .Background
let moreAction = UIMutableUserNotificationAction()
moreAction.title = "Emoji"
moreAction.identifier = "EmojiAction"
moreAction.destructive = false
moreAction.authenticationRequired = false
moreAction.activationMode = .Background
return [stopAction,moreAction]
}
func makeCategory()-> UIMutableUserNotificationCategory {
let category = UIMutableUserNotificationCategory()
category.identifier = "Nags"
category.setActions(makeActions(), forContext: .Default)
return category
}
}
AppDelegate.swift
//
// AppDelegate.swift
// PhoneWatchNotificationDemo
//
// Created by Steven Lipton on 5/1/16.
// Copyright © 2016 MakeAppPie.Com. All rights reserved.
//
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
let category = naggingNotification.makeCategory()
application.registerUserNotificationSettings(
UIUserNotificationSettings(
forTypes:[.Alert, .Sound],
categories: [category]
)
)
return true
}
func application(application: UIApplication, handleActionWithIdentifier identifier: String?, forLocalNotification notification: UILocalNotification, completionHandler: () -> Void) {
if notification.category == "Nags"{
if identifier == "StopAction"{
naggingNotification.stopTimer()
}
if identifier == "EmojiAction"{
naggingNotification.toggleAlertMessages()
}
}
completionHandler()
}
func applicationDidBecomeActive(application: UIApplication) {
let rvc = window?.rootViewController as! ViewController
rvc.stateDidChange() //Update the button
}
}
ViewController.swift
//
// ViewController.swift
// PhoneWatchNotificationDemo
//
// Created by Steven Lipton on 5/1/16.
// Copyright © 2016 MakeAppPie.Com. All rights reserved.
//
import UIKit
class ViewController: UIViewController {
@IBOutlet weak var nagButton: UIButton!
@IBAction func nagButton(sender: UIButton) {
if naggingNotification.nagging{
naggingNotification.stopTimer()
}else{
naggingNotification.startTimer(10.0)
}
stateDidChange()
}
func stateDidChange(){
if !naggingNotification.nagging{
nagButton.setTitle("Nag", forState: .Normal)
}else{
nagButton.setTitle("Stop Nagging", forState: .Normal)
}
}
}
