In iOS application, I want to upload data on server when internet available. Now problem is, if user has force quit the application then how I can re-invoke the application or can do task in background when internet is available? Is there any possible way in iOS?
Apple is not allowing to run code after the user force quits the app. There are just some special rules to reactivate the app like blutooth implementation. For normal server task, you just can work while the user not force quits the app.
Edit
Not even with special rules you can reactivate your app. Bluetooth reactivation and co only works if the app gets killed by memory issues or something similiar. If the user force quits the app, the app will not run until next app start.
The iOS will give you 3mins to run a background task. Take a look at https://medium.com/#abhimuralidharan/finite-length-tasks-in-background-ios-swift-60f2db4fa01b
Related
My application requires periodic location updates (every 10 minutes). In foreground and background (app not terminated) the application is working correctly. But the problem starts to occur when the app is terminated by the user.
I tried using this tutorial http://mobileoop.com/getting-location-updates-for-ios-7-and-8-when-the-app-is-killedterminatedsuspended .
It works only when user's location is changing because of startMonitoringSignificantLocationChanges. But I need locations in terminated state even if user is not changing its location.
Also, I have tried most of the stackoverflow questions but most of them gets satisfied with startMonitoringSignificantLocationChanges. But in my case it won't be enough to fulfil the application needs.
If a user terminates the app the system no longer grants it the same privileges. Background fetch operations and background location will not get executed until the user decides to start up your app again. The system recognizes this a user choice to not have this app running in any way again.
This isn't like the world of Android where an app can do as it pleases. Apple prefers user choice over what an app developer wants. This is of course good and bad as a developer. You need to provide the user with useful information about what your app is doing in the background so that they will allow it to run without terminating it. If they do terminate it, there is nothing that you can do.
First of all i need to describe what i am going to do: when user launch my application the app start collecting statistics about the user activities and behavior, once the the user close the app (app enter background) the application upload all statistics to server.
the problem if the user presses home button twice and removes application from multitasking screen. then the application may not succeed to send statistics to server. because it will be terminated.
my solutions:
enable Background fetch , in background modes. but I don't think that will help because according to apple: the system does not relaunch apps after they are force quit by the user
using Executing Finite-Length Tasks , i tried it , it won't send the data if user remove the app from multitasking screen.
using NSURLSession to Downloading Content in the Background, but according to apple If the user terminates your app, the system cancels any pending tasks.
so all above solutions will not work if user terminate the application, any solution ?
I noticed that if i terminate the appstore app (remove it from multitasking screen ) while there is an application being downloaded , the application will continue downloading normally. is this just for appstore app ?
If the user terminates an app, the app terminates. There is nothing you can do about this. iOS devices are meant to be controllable by the user.
Depending on what you are trying to achieve, you might add all the statistics to a queue on disk, and empty that queue only after the app has successfully uploaded the data to the server.
If the user doesn't force-quit, this will work at once, in just the way you want.
If the user does force-quit, the data will not be uploaded and the queue will still be present on disk. When the app is started, it can check the queue and upload it immediately.
You ought to be doing something like this in any case, to deal with cases like the user going underground for an hour, or taking a long-distance flight.
I suspect that the App Store app does not install apps, but tells a system process to install them.
My application requires periodic location updates (every 10 minutes). In foreground and background (app not terminated) the application is working correctly. But the problem starts to occur when the app is terminated by the user.
I tried using this tutorial http://mobileoop.com/getting-location-updates-for-ios-7-and-8-when-the-app-is-killedterminatedsuspended .
It works only when user's location is changing because of startMonitoringSignificantLocationChanges. But I need locations in terminated state even if user is not changing its location.
Also, I have tried most of the stackoverflow questions but most of them gets satisfied with startMonitoringSignificantLocationChanges. But in my case it won't be enough to fulfil the application needs.
If a user terminates the app the system no longer grants it the same privileges. Background fetch operations and background location will not get executed until the user decides to start up your app again. The system recognizes this a user choice to not have this app running in any way again.
This isn't like the world of Android where an app can do as it pleases. Apple prefers user choice over what an app developer wants. This is of course good and bad as a developer. You need to provide the user with useful information about what your app is doing in the background so that they will allow it to run without terminating it. If they do terminate it, there is nothing that you can do.
I'm little bit confused with background fetch. I read in Apple Developer documentation that fetch happens when OS decides that it should, user can't control background fetch, while on Apple Developer forum post by Apple employee says that if user kills app (double tap on home and button swipe up) background fetch wont happen, in that case user can control background fetch. So can someone please clarify to me if user kills the app with task manager will background fetch still continue in the background or it's killed at the same time as app.
Apple documentation:
https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html#//apple_ref/doc/uid/TP40007072-CH4-SW1
From the doc you link:
When a good opportunity arises, the system wakes or launches your app into the background and calls the app delegate’s application:performFetchWithCompletionHandler: method.
So, it seems that the system is able to launch in the background an app that is not running so it executes a background fetch. On the other hand, though, later in the document you can read:
In most cases, the system does not relaunch apps after they are force quit by the user. One exception is location apps, which in iOS 8 and later are relaunched after being force quit by the user. In other cases, though, the user must launch the app explicitly or reboot the device before the app can be launched automatically into the background by the system.
So, Apple's engineer is right: force quitting an app puts it into a sort of special case where background fetches are not allowed anymore.
If the user feels the need to allow background operations, he wouldn't kill the app. But when he kills it, it is only appropriate to disallow background fetch. User can only control if background fetch should happen or not by allowing it to stay in background/by killing the app. But once the app is in background, user cannot control "when" the background fetch happens. The OS determines it based on how free it is.
I think this quote (from the linked document) is the most important for the scenario you're describing:
Once configured, your NSURLSession object seamlessly hands off upload and download tasks to the system at appropriate times. If tasks finish while your app is still running (either in the foreground or the background), the session object notifies its delegate in the usual way. If tasks have not yet finished and the system terminates your app, the system automatically continues managing the tasks in the background. If the user terminates your app, the system cancels any pending tasks.
Is it possible to send the application to background programmatically on iPhone?
Under iOS 4.0, your app will be put in the background if another app enters the foreground, and there are enough resources to keep your app in the background. You could send a URL to Safari, or another app that has registered for a handler, and hope that there's enough memory (etc.) that the OS puts your app in the background after it starts Safari (or whatever app handled the URL). If you are lucky (which typically happens fairly often), you will have sent your app programmatically to the background.
Of course, whether your app runs in the background, or is just suspended, depends on other things (which you have to register with iOS 4.x for).
Apple does allow apps to exit (kill themselves) programmatically. But it's meant only as a last resort for when something bad happens from which your app cannot recover.
On all other occasions, apps are expected to stay in the foreground and running until either the user presses the home button or the app opens another app, with the users consent.
Actually you don't want to kill the app, however moving it to the background and returning to the home screen would leave a very similar impression. That's why I don't think Apple would approve it and consequently doesn't offer, as far as I know, any means to move an app to the background programmatically without opening another app.
No it is not possible. Only iOS can put your application in the background.
Note that there's a lot of confusion between "background" and "inactive". An inactive application is one that is not displayed on the GUI but is still running.
Technically an application in the background isn't running; it's dormant. Depending on the mode used, a background applications can receive signals and "wake up." See Background Modes for more details: https://developer.apple.com/library/ios/documentation/general/Reference/InfoPlistKeyReference/Articles/iPhoneOSKeys.html#//apple_ref/doc/uid/TP40009252-SW22
But a background application can also get terminated at any point without warning. As a matter of fact I always treat a background application as terminated. Therefore you should always clean up your application before you enter the background, and re-initialize it when you enter the foreground.
This is a must-read on this topic: https://developer.apple.com/library/ios/documentation/iphone/conceptual/iphoneosprogrammingguide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html
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