Is there a way to persist an iOS app in the background such that it starts up automatically when the device is turned on and will re-launch later if terminated? I have read a few posts on either voip and gps services. My app sends emergency SMS messages with the user's location. It needs to remain active to listen for distress triggers. Would it be possibly to start up the app automatically with sending push notifications to the app using an APNS server?
Yes, you can start your app using APNS.
1) You have to set "content-available" to 1 in the notification body.
2) You have to implement:
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
3) And have the right background modes: Background Modes
But be careful, your users can turn this off by disabling Background App Refresh in the iPhone Settings. You can check this in code:
[UIApplication sharedApplication].backgroundRefreshStatus!=UIBackgroundRefreshStatusAvailable
Related
I have an app and a server-side push sender. When new notifications arrive, the server sends an empty push message which only contains a badge update.
When the app is in the background, the badge is successfully updated. However, when the app is in the foreground, the badge is not updated at all - the push is delivered to the app, which discards it.
The obvious workaround is to catch the push and update the badge from within the app. For some technical reasons this would take some time to take effect (development time, app store check time, users who don't frequently upgrade etc.)
I wonder if there's a way to circumnavigate this and update the badge using a server side APNs push regardless of the app state, foreground or background.
Is there a way to change an iOS app badge using a push message, when the app is in the foreground, without handling the push notification from within the app?
This can only be achieved through application delegate methods defined in your AppDelegate
Deprecated in iOS 10
- (void) application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo;
or,
- (void)application:(UIApplication *)application
didReceiveRemoteNotification:(NSDictionary *)userInfo
fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler;
The above delegate functions gets called when app is in foreground there you can decode your Push Payload and assign the application badge as follows
[UIApplication sharedApplication].applicationIconBadgeNumber=[[userInfo objectForKey:#"aps"] valueForKey:#"badge"];
Cheers.
I was wondering if there was a way to wake up an app that has been terminated by the user on ios8-9. By terminated I mean double click on the home button and swipe up.
Is it somehow possible to launch an app by sending a silent push notification so that didreceiveremotenotification gets fired and gives me some runtime ?
I have noticed that a fair share of my users terminate my app. As I rely heavily on background fetch, this a problem. My idea was to send silent push notifications to launch the app in the background and trigger background fetch.
Short Answer: No That is not possible.
Detail:
When there is any new content on server you will send Remote Notification to your application to inform about that. (A Remote Notification is really just a normal Push Notification with the content-available flag set)
When application received this Remote Notification it calls following method:
- (void)application:(UIApplication *)application
didReceiveRemoteNotification:(NSDictionary *)userInfo
fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))handler
In Documentation of this method it is clearly written:
However, the system does not automatically launch your app if the user
has force-quit it. In that situation, the user must relaunch your app
or restart the device before the system attempts to launch your app
automatically again.
Reference:
objc.io: Remote Notifications
Apple Doc about application:didReceiveRemoteNotification:fetchCompletionHandler:
I am trying to achieve silent push notification.I need to save the silent push notification data in my database in app so that I can show the unseen notification and its count to users when the users uses the app.
I am using Xcode 6.1 and targeting iOS 7 and later devices. Currently, I am using development certificates for push notification.
I have checked remote notification in the background modes of target project capabilities, also the info-list's background mode has "App downloads content in response to push notifications" in required background modes.
In my AppDelegate.m, I am able to register remote notification and also get the device token. Now when I send push notification, my delegate method gets called when app is in foreground but when app is in background/not running, it doesn't get called though I receive the push notification in banner.
I have implemented this method in AppDelegate.m
-(void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler{
NSLog(#"Received push notification");
}
The payload I am sending looks like this:
{
aps: {
content-available: 1
}
}
I tried adding priority, sound etc. But nothing helped me.
Can someone help me to figure out how to save silent push notification data in app when app is in running in the background or not running?
Kindly help me to resolve this issue.
So, you should definitely be able to receive them in the background, but be warned that if the user deliberately kills your app from the task switcher then it won't get them anymore.
With iOS 7 and above the callback is as you say, but before that it was
- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken
Seems unlikely you are targeting iOS 6 though so I would go with either a malformed push packet or background push settings not being quite right.
Do you have the apps info.plistUIBackgroundModes set to remote-notificiton?
Then also add this method to help you debug
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))handler
{
//Success
handler(UIBackgroundFetchResultNewData);
}
Silent push notifications are different than user-facing notifications. They are treated as low priority and are rate limited by both APNS and iOS. In practice, this means that silent notifications can only be sent infrequently and there may be a very long delay before they are delivered to an application.
The behavior you are describing is likely the wakeup rate limiter on the device. iOS limits how often apps are launched to perform background work. This is to prevent abusive behavior - some apps might want to stay alive in the background draining the battery forever.
The wakeup rate limiter is not active when Xcode is attached, which makes silent notifications appear to be delivered instantly.
My iOS Notifications book has a lengthy chapter describing the rate limiters and how to work with them.
There's a new feature in iOS 8: using a push notification to wake an app, which also lets the app refresh data in the background. How do I use this feature?
The push notification arrives with a value of 1 for the key 'content-available'. However, no data is received if the app is not already running in background. Why not?
There are couple of things here,
1.U need to check Remote Notification on under Background mode of the target in Capabilities section.
2.U need to implement below method,
-(void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
Is it possible to call a certain method from the AppDelegate after a push notification has been received while the app is in inactive state (Terminated)?
I know it is possible to call a method when the app is opened from the notification (eg. tapping a banner in notification center.)
I'd like to perform a small geolocation check when a push is received from my server. Is that possible and wont my app get rejected?
You can handle a push notification in
- (void)application:(UIApplication *)application
didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler
when app is in background state and working, not inactive.
But you can send a sound & text notification when app is inactive but you can't do anything.
Inactive I mean suspended - not working at all (neither foreground nor background).
It is not possible. Your app badge will only be updated if you are sending it from the server.
There is no API that allows doing something after push on inactive app without user interactions
Apple says: "Inactive State:: The app is running in the foreground but is currently not receiving events. (It may be executing other code though.) An app usually stays in this state only briefly as it transitions to a different state."
So It's not possible that you want.