I have an app which crashes everytime when I resume it.
I want that when user clicks Home button, the app should close rather than go in background mode.
Is that possible?
If yes, please let me know.
If not, what could be the workaround so that my app does not crash when I resume it?
Thanks!
In the plist, set YES to Application does not run in background key.
When ur application is in background, due to memory insufficient, the views (and the objects released in viewDidUnload) might be released. Again when reopen the application, make sure all the required objects are re-initialized.
To opt out of background execution, see this thread... But ideally what you should do is fix the crash and let app user enjoy iOS background feature..
what could be the workaround so that my app does not crash when I
resume it?
Never think of work arounds when you can handle it straight..
Related
My IOS 14 app is always being killed immediately when it is being minimized. I have already added background modes: background fetch and background processing. However, when the app goes into the background and I switch to another app, XCode is telling me this:
Snapshotting a view (0x7f91ed844000, UIKeyboardImpl) that has not been rendered at least once requires afterScreenUpdates:YES
So I thought maybe the app can't create screenshots for the app switcher and Apple then just kills the app. My problem is that the message doesn't tell me how I can add this to the view. The documentation doesn't help me either also Google and searching here doesn't help. Everything I find is about how to take a screenshot and save it somewhere which is not what I am trying to do. Does anyone have an idea how I can approach this problem?
Thank you very much!
If I send my app to background by clicking the home button and wait a certain time (perhaps 1 or 2 hours).
What will happen if i tap on the app icon now?
Will the app relaunch or simply be brought from background to foreground?
Quick "prologue":
Welcome to the wonderful world of stack overflow (SO), I myself am rather new here, but found it much friendlier to use welcome you anyway!
Just in case you haven't: Before you ask a question please look around a bit on SO in case someone else has asked the same thing, but if you can't get your question answered from that, then you should of course ask your own question.
Answer:
This question has no definite answer, because it depends. When you tap the home button your app enters, as you've said, the background and is still running to a certain degree. However after done so, the apps life cycle is up to iOS (the devices operating system) to determine. iOS controls and checks memory and CPU usage (etc..) of the device, and if you start another activity while your app is in the background that makes the available memory and CPU etc of the device not sufficient, iOS will terminate any apps in the background to not waste those resources (or battery etc). If so your app will relaunch next time you tap on it.
Although if you don't do anything performance heavy it is more likely that iOS keeps your device running in the background.
I'm not sure about the exact conditions and such the iOS works on, but i would say its very likely your app will have gotten terminated and is relaunched after 1 or 2 hours "in the background". Additional conditions apply if the device is locked during that period.
For proper documentation of this i would recommend reading Apples documentation for handling App State Transitions and/or the api for UIApplicationDelegate on apples developer website. Where you can see what the different methods in the AppDelegate does and how they interact.
Edit (answer to comment):
A way to relaunch the app everytime it goes into background?
Hm, yes, but also no. I'm not 100% sure about this (never encountered that "wish" before), but you can do this in your AppDelegate: (It will basically crash your app, but beware that apple does not encourage you to crash your own app anywhere). Doing this might stop the app from passing through apple store review process (i.e. your app might not be accepted to the App Store).
func applicationDidEnterBackground(_ application: UIApplication) {
exit(0)
}
Check out the answer to these post for a bit more information: call exit(0) in iphone app , objc - Proper way to exit iPhone application?.
Personally I would recommend you to work around it and don't do this. Also remember that when your app will enter the background applicationWillResignActive will be called and when the user opens it again, applicationDidBecomeActive gets called so you can do a reload or something from there if you want to refresh any data.
Whenever we press the home button in our device, the application releases the currently being used memory and moves to background stage. However, when we press this application app icon again it brings the app on top of the iPhone screen and occupies memory again. This is definitely not the relaunch because relaunch depends upon the UIApplicationDelegate method
didFinishLaunchingWithOptions. When we are switching app from background to foreground then applicationWillEnterForeground method fires.
For better understanding, the following link might be useful
iOS Application Life Cycle
I want to run a function when my application opens from the background (after someone has pressed home button and reopened the app).
I have been told to look into "NSNotificationcenter" and "applicationdidbecomeactive", but I have no idea how to use those. And yes I have been searching online.. Can anyone please help me with this one?
In your Appdelegate class there are methods which invoke on app becoming active and going to background.Do code in them to do things which you want to do when the app goes to background or becomes active.
I'm developing an app on iOS 7 with a desired feature is that
When I home button, app enter background, I will add an image to current UIWindow. So when app enter background, if user double home button on iOS 7, os will show a small screenshot of current view of my app, so user can see my added image. :) (I did it)
When user return my app by clicking app icon, I want to remove this image immediately. In this situation, "immediately" means that user can NOT see this image anymore, user just see his/her current view when app enter foreground. I try to place the code remove image on the beginning of applicationWillEnterForeground delegate, but I'm still able to see this image for a short time after it disappears.
I also try to set hidden, alpha property for this imageview first, then removeFromSuperview, but it not works.
Can anyone help me to remove it "immediately" as my desire.
That is done automatically for all applications, you don't need to do anything in you code.
I don't think that you can do it faster, it depends of device performance. Sorry man.
Like other says it is really tricky how iOS handles these events. I've been researching and depends on the memory state of the device to do it faster or not. Indeed, in iPhone 4 and 4S may not show the image that you added on applicationWillEnterForeground method.
If I were you I would solve it by adding a smooth fade out animation of that image when the app becomes active again. With [UIView animateWithDuration: animations:] it could be nicely done! :)
If I find out something else I'll answer here!
I my testing, when I exit (by pressing the home button) my app, it still is "running" in the background, thanks to the multitasking feature. However, I would like it to quit when the home button is pressed. Is this only happening to me?
Anyway, I have tracked it down to the applicationWillResignActive and the applicationDidBecomeActive methods in the app delegate. These get called for multitasking, but when I want to terminate, the app "resigns active." Any guidance on this issue is greatly appreciated!
Your application can opt out of multitasking (see the appropriate section in the iPhone Application Programming Guide) by adding the UIApplicationExitsOnSuspend key to your Info.plist and setting its value to YES.
In practice, Apple strongly recommends you not do this unless you have a very good reason for this behavior.
I think it's more efficient to suspend an app, when pressing the "Home" button. There's overhead in constantly launching and terminating apps. It's worse for the iOS operating system, and it's worse for user experience - because they need to wait for the app to launch again. Not sure what benefits you gain from terminating an app. If it's for simulation testing, my advice is to avoid that functionality, because your testing environment should be as realistic as possible. If your purpose is to clear cache or to make updates - that can all be done programmatically from subroutines.
Exiting subroutines
applicationWillResignActive
applicationDidEnterBackground
applicationWillTerminate
Entering subroutines
applicationDidBecomeActive
applicationWillEnterForeground
applicatonDidFinishLaunching
If you still insist on terminating an app when the user presses the "Home" button, despite the costs mentioned above - then set the UIApplicationExitsOnSuspend to true in your Info.plist as suggested by Brad Larson.
I wouldn't recommend trying to control the user's HOME button... deciding for them "exit" or "suspend".
I WOULD like to have HOME do an instant EXIT in the iPhone simulator... but haven't found any way to do that.