I did some research on lots of stackoverflow issues and websites in trying to figure out how do the iOS push notifications influence AppDelegate lifecycle methods and when is which method (not) getting triggered. Main focus of the research was on "standard" iOS push notifications (with alert field) and silent ones (with just content-available set to 1) and on AppDelegate's application:didReceiveRemoteNotification and application:didFinishLaunchingWithOptions methods.
I don't want to ask lots of questions for different scenarios, but would rather try to write down the statements about different test cases I tried and ask you after that:
Is there any statement that is wrong and if yes, which one and why?
Scenario 1: App has been used and put to background by tapping the home button.
If standard push notification is sent, in the moment of push notification arrival, none of the methods gets triggered, app remains inactive in background. Once push notification has been tapped and app got opened because of it, application:didReceiveRemoteNotification method got called and application:didFinishLaunchingWithOptions doesn't get called. I tested this scenario right after putting the app to background and also after an app being in background for more than an hour - same behaviour. I guess that if for some reason iOS decided to kill my app while being in background, this test case becomes like Scenario 2, statement 1 from below, right?
If silent push notification is sent, in the moment of the push notification arrival, application:didReceiveRemoteNotification method got called and application:didFinishLaunchingWithOptions doesn't get called.
Scenario 2: App has been used and killed by swiping it out of the list of running apps.
If standard push notification is sent, in the moment of push notification arrival, none of the methods get triggered, app remains killed. Once push notification has been tapped and app got opened because of it, application:didReceiveRemoteNotification method got called and application:didFinishLaunchingWithOptions doesn't get called.
If silent push notification is sent, none of the methods gets triggered since silent push notifications fail to be sent to the app that got killed. After opening an app after notification is sent, application:didFinishLaunchingWithOptions gets called as part of the normal flow and without any push notification information. application:didReceiveRemoteNotification doesn't get called.
If you can maybe think of some other real life scenarios that I maybe forgot to mention, I would be really grateful to find out about them and what happens in those cases.
Cheers
Update #1
Thanks to Sandeep Bhandari for the update and additional scenarios. I forgot to mention in my original question that I was exploring scenarios in which application is arriving to the app that is currently not in the foreground for whatever reason.
Adding Sandeep's scenarios to the list:
Scenario 3: App is being used and push notification arrives.
If standard push notification is sent application:didReceiveRemoteNotification method will get called. application:didFinishLaunchingWithOptions will not get called.
If silent push notification is sent application:didReceiveRemoteNotification method will get called. application:didFinishLaunchingWithOptions will not get called.
Scenario 4: App being alive in background.
If standard push notification is sent application:didReceiveRemoteNotification method will get called. application:didFinishLaunchingWithOptions will not get called.
If silent push notification is sent application:didReceiveRemoteNotification method will get called. application:didFinishLaunchingWithOptions will not get called.
From an experience and digging alot on the iOS push notification. App
being in foreground or alive in background. both situations triggers
same delegate methods. only didReceiveRemoteNotification.
The silent push notification have a different handler: (content-available 1 means silent notification)
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
}
When app is dead. didReceiveRemoteNotification never called for regular push notification. It must be handled in didFinishLaunchingWithOptions as following:
// handle notification when app is closed.
let notification = launchOptions?[.remoteNotification]
if notification != nil {
self.application(application, didReceiveRemoteNotification: notification as! [AnyHashable : Any])
}
Additional information:
To test receiving push notification when app is killed. remove from the list that appears when double tapping home button?
The proper way to see the logging and do debugging is by editting the run scheme and selecting Wait for executable to be launched:
Run the app from the xcode. Then send push notification from server and then tap the notification from notification center.
I don't see any issue in the statement you made there, but I believe you missed to iterate over two more scenarios that I can think of.
App is in foreground and receives the push notification : didReceiveRemoteNotification gets called as soon as APNS gets delievered to iOS and you can handle it by checking application state in didRecieveRemoteNotification Method.
App being alive in background : I believe you are aware of background modes of iOS. If app is making use of expiration handler, app will be alive even if you put it to background by tapping on home button. Duration the app lives in background depends on various factors (some tutorials say app remains alive for 3 mins which I can't guarantee) Even in this case didReceiveRemoteNotification gets called as soon as APNS gets delievered to iOS. Only this time app wont be in foreground but yet its alive!!!
Related
I am working on a reminder app.The app will show notifications at particular times which is set by the user.I have used local notifications to show the reminder.
The problem is I want to run some codes when it receives the local notifications even if the user does not tap on the notification. Is there any way to do this in swift ?
I believe you should add method application(_ application: UIApplication, didReceive notification: UILocalNotification) inside your AppDelegate.swift. The code you want to be implemented should be there. The code will be executed even the user does not tap on the notification. But anyhow, the app should be running.
Here is an extract from apple docs:
If
the app is not active in the foreground when the notification fires,
the system uses the information in the UILocalNotification object to
determine whether it should display an alert, badge the app icon, or
play a sound. If the app is running in the foreground, the system
calls this method directly without alerting the user in any way.
You might implement this method in your delegate if you want to be
notified that a local notification occurred. For example, a calendar
app might use local notifications to alert the user to upcoming
events.
If the user chooses to open the app when a local notification occurs,
the launch options dictionary passed to the
application(:willFinishLaunchingWithOptions:) and
application(:didFinishLaunchingWithOptions:) methods contains the
localNotification key. This method is called at some point after your
delegate’s application(_:didFinishLaunchingWithOptions:) method.
How can I call the method didReceiveRemoteNotification in didfinishlaunchingwithoptions? I'm using swift language.
when the user directly opens the app, the notification cancelled and the operations performed in didReceiveRemoteNotification not called. How to handle this ?
I've reached upto here. But unable to complete
if let options = launchOptions, notification = options[UIApplicationLaunchOptionsRemoteNotificationKey] as? [NSObject : AnyObject] {
self.application(application, didReceiveRemoteNotification: notification, fetchCompletionHandler: _______)
}
As per docs,
The notification is delivered when the app isn’t running in the
foreground. In this case, the system presents the notification,
displaying an alert, badging an icon, perhaps playing a sound, and
perhaps displaying one or more action buttons for the user to tap.
The user taps a custom action button in an iOS 8 notification. In this
case, iOS calls either
application:handleActionWithIdentifier:forRemoteNotification:completionHandler:
or
application:handleActionWithIdentifier:forLocalNotification:completionHandler:.
In both methods, you get the identifier of the action so that you can
determine which button the user tapped. You also get either the remote
or local notification object, so that you can retrieve any information
you need to handle the action.
The user taps the default button in the alert or taps (or clicks) the
app icon. If the default action button is tapped (on a device running
iOS), the system launches the app and the app calls its delegate’s
application:didFinishLaunchingWithOptions: method, passing in the
notification payload (for remote notifications) or the
local-notification object (for local notifications). Although
application:didFinishLaunchingWithOptions: isn’t the best place to
handle the notification, getting the payload at this point gives you
the opportunity to start the update process before your handler method
is called.
For remote notifications, the system also calls the
application:didReceiveRemoteNotification:fetchCompletionHandler:
method of the app delegate.
If the app icon is clicked on a computer running OS X, the app calls
the delegate’s applicationDidFinishLaunching: method in which the
delegate can obtain the remote-notification payload. If the app icon
is tapped on a device running iOS, the app calls the same method, but
furnishes no information about the notification.
The notification is delivered when the app is running in the
foreground. The app calls the
application:didReceiveRemoteNotification:fetchCompletionHandler: or
application:didReceiveLocalNotification: method of the app delegate.
(If application:didReceiveRemoteNotification:fetchCompletionHandler:
isn’t implemented, the system calls
application:didReceiveRemoteNotification:.) In OS X, the system calls
application:didReceiveRemoteNotification:.
You can find the link for the same in here :
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/IPhoneOSClientImp.html#//apple_ref/doc/uid/TP40008194-CH103-SW1
Summary :
You have to handle APNS in 3 situations :
App is in Foreground/App is in background (but not suspended) : application:didReceiveRemoteNotification: method of the app delegate is called and payload is handed over to you.
2.App is suspended/killed and user taps on notification or Alert: application:didFinishLaunchingWithOptions: of app delegate gets called and you can access payload from launchOption.
3.App is suspended/killed and user taps on App Icon : You will not receive any info about APNS. Simplest solution you can do is once the app becomes active make a web service call to web server fetch all the updated info and update your UI and application badge count :)
Hope it helps :)
I'm facing a problem with push notifications, I'm using Google Cloud Messaging,
My problem is that my app works with some cached data, and I refresh that cache with the data coming from push notificacions, so when the app is killed by the user (home button + swipe-up) and the app receive a push notification it doesn't call the method didReceiveRemoteNotification, so the app can't access to the payload of that notification and update the cached data.
So, is there a way to achieve this?
Only when the user taps the notifications and the app gets it through the application:didFinishLaunchingWithOptions method?
If the user opens the app by clicking the application icon I can't get the notificaton's payload?
PD: If the app is in foreground or background (not killed) it works perfectly
If you wish your app to receive the push notification even when it is killed, add the key "content-available":"1" to the push payload.
Look here
EDIT:
After digging some more, I found out that silent push (e.g content-available:1), does not wake the app if it was killed by the user:
However, the system does not automatically launch your app if the user has force-quit it
I must say, I can't really understand why the OS does not let my app wake up when silent push arrives when it's dead. What's the point then???
This is the expected behavior. didReceiveRemoteNotification will not be called if the user killed the app, unless your app has VoIP permissions.
In case of killed application. both application:didFinishLaunchingWithOptionsandapplication:didReceiveRemoteNotification:fetchCompletionHandler:are called. In the prior one. The key of notification either remote or local is passed in options parameter. And the later one is called in only case when remote notification. The process is explained in detail in Apple Docs Here. The snapshot is pasted here as well.
Handling an Actionable Notification
If your app is not running in the foreground, to handle the default action when a user just swipes or taps on a notification, iOS launches your app in the foreground and calls the UIApplicationDelegate method application:didFinishLaunchingWithOptions: passing in the local notification or the remote notification in the options dictionary. In the remote notification case, the system also calls application:didReceiveRemoteNotification:fetchCompletionHandler:.
If your app is already in the foreground, iOS does not show the notification. Instead, to handle the default action, it calls one of the UIApplicationDelegate methods application:didReceiveLocalNotification: or application:didReceiveRemoteNotification:fetchCompletionHandler:. (If you don’t implement application:didReceiveRemoteNotification:fetchCompletionHandler:, iOS calls application:didReceiveRemoteNotification:.)
Finally, to handle the custom actions available in iOS 8 or newer , you need to implement at least one of two new methods on your app delegate, application:handleActionWithIdentifier:forRemoteNotification:completionHandler: or application:handleActionWithIdentifier:forLocalNotification:completionHandler:. In either case, you receive the action identifier, which you can use to determine what action was tapped. You also receive the notification, remote or local, which you can use to retrieve any information you need to handle that action. Finally, the system passes you the completion handler, which you must call when you finish handling the action. Listing 2-8 shows an example implementation that calls a self-defined action handler method. Reference Apple Docs
Edit:
The user taps the default button in the alert or taps (or clicks) the app icon. If the default action button is tapped (on a device running iOS), the system launches the app and the app calls its delegate’s application:didFinishLaunchingWithOptions: method, passing in the notification payload (for remote notifications) or the local-notification object (for local notifications). Although application:didFinishLaunchingWithOptions: isn’t the best place to handle the notification, getting the payload at this point gives you the opportunity to start the update process before your handler method is called.
Reference: Apple Docs
When the app is killed and the push notification triggered contains some actionable button. When we click on a Action Button of Push Notification then:
The first delegate that is executed is:
-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
But in here the launchOptions are nil.
The second delegate that is executed is:
-(void)application:(UIApplication *)application handleActionWithIdentifier:(nullable NSString *)identifier forRemoteNotification:(nonnull NSDictionary *)userInfo completionHandler:(nonnull void (^)())completionHandler
In this the variable userInfo contains all the payload of the Push Notification. With the help of identifier we can identify which action was invoked and then perform our respective operations.
add target of notification service extension in your project it contains two methods upper one method call in killed time and add a key "mutable_content" : true in server side of your notification payload
My app schedules a local notification with two actions on a specific time.
By the time it arrives on the phone (few hours later) my app is already in a suspended state and pressing any action button leads to nothing or simply crashes the app.
In documentation i've read that didReceiveRemoteNotification method works for handling such tasks and waking up the app from the suspended state, but i have no idea how to implement it properly for actions.
Thank you!
didReceiveRemoteNotification is called when you receive a push notification via APNS. You should be using a handler for didReceiveLocalNotification in your AppDelegate.
This is my scenario:
My application is not launched yet at that time app receives push notification from APN which delegate method get called;
what I read:
1. If app is in background or foreground DidReceiveRemoteNotification get called.
2. If app is not launch yet then the notification will be received in banner if i click on it. App will launch from didFinishLaunching with notification option.
You can try silent push notification. If app is in killed state, slient push notifications will be called.
Silent push will call delegate in any state.
you need pass: 'content-available' => '1' with the payload for silent notification.
Just the limit is it supports ios7 and higher.
if i understand your question correctly then solution below
when your application is not launched yet (not runnable state) that time there is not delegate method called (there is no delegate method available.)
if you want to do something after receiving push notification at that time (not runnable state or suspended state) IOS 7 provide two method
" setMinimumBackgroundFetchInterval: "
"application:performFetchWithCompletionHandler:"