In application that I work on it, I need to close it from code. I'm using exit(0) for that.
Yes, I know that i shouldn't close application from code
When I close application in this way, and run it again, there is some strange behaviur - application doesn't start nor from splash screen, like new instance of app, neither from last view, like application turning back from background.
Instead, for a second some random, non-interactive view of my app is appearing, and after this splash screen start to run.
I'm confused because I cannot find source, and how to fix this ugly bug. Can you help me?
This is exactly the problem with exit(0). You get weird multitasking behaviour and all sorts of other problems.
You simply can't terminate your application in code. You should explain to us why you think you need to quit programmatically so we can help you find an alternative solution.
From Technical Q&A QA1561
There is no API provided for gracefully terminating an iOS application.
Do not call the exit function. Applications calling exit will appear
to the user to have crashed, rather than performing a graceful
termination and animating back to the Home screen.
Additionally, data may not be saved, because
-applicationWillTerminate: and similar UIApplicationDelegate methods will not be invoked
if you call exit. If during development or testing
it is necessary to terminate your application, the abort function, or
assert macro is recommended.
Instead of
exit(0)
try this:
[[UIApplication sharedApplication] performSelector:#selector(terminateWithSuccess)];
Related
I am building a word game and I want to hide the board when application is suspended?
the code looks fine however it givs a strange behaviour!!,
when I suspend the app nothing will happen but when i resume the application then the board will hide!!
local onSystem = function( event )
if event.type == "applicationSuspend" then
print("suspend")
board_group.alpha = 0
end
end
Runtime:addEventListener( "system", onSystem )
Note: you might wonder how do I know how the application looks when suspended?
the answer is: by pressing the home button twice.
example
SpellTower in normal state
https://dzwonsemrish7.cloudfront.net/items/430k0c0b0y0b413d0b42/Image%202012.11.12%208:08:24%20AM.png?v=4822f549
SpellTower after pressing the home button twice
https://dzwonsemrish7.cloudfront.net/items/280a1y0r2U3W321y1B2z/Image%202012.11.12%208:08:31%20AM.png?v=09c37567
you can see how they are hiding the letters, this is exactly what I want to do for my game, the only difference is i am using Corona SDK
When you do board_group.alpha = 0 you only has set a variable, the result will only take effect after a screen update.
But since the application is suspended... it won't update! So, changing any graphics on applicationSuspend don't work.
I believe the reason is because the application is not considered as suspended. In normal objective c programming it means that applicationWillResignActive is called when the user double clicks on the home button. So what you want to do is to add that code for this part.
Here is a flow of events:
http://www.cocoanetics.com/2010/07/understanding-ios-4-backgrounding-and-delegate-messaging/
Corona seems to have these events:
"applicationStart" occurs when the application is launched and all code
in main.lua is executed.
"applicationExit" occurs when the user quits the application.
"applicationSuspend" occurs when the device needs to suspend the application such as during a phone call or if the phone goes to sleep
from inactivity. In the simulator, this corresponds to the simulator
running in the background. During suspension, no events (not even
enterFrame events) are sent to the application while suspended, so if
you have code that depends on time, you should account for the time
lost to an application being suspended.
"applicationResume" occurs when the application resumes after a suspend. On the phone, this occurs if the application was suspended
because of a phone call. On the simulator, this occurs when the simulator was in the background and now is the foreground application.
So my guess is that you have to implement it outside of the corona API.
According to the corona documents you can implement them in the delegate:
You can intercept UIApplicationDelegate events via your implementation
of the CoronaDelegate protocol.
This protocol conforms to the UIApplicationDelegate protocol. Corona's
internal delegate will call your protocol's method if it is
implemented.
Please keep in mind the following:
Methods that Apple has deprecated will be ignored.
In most cases, your class' version will be invoked after Corona's corresponding version of the UIApplicationDelegate method. There is one situation in which your version will be called before.
In situations where the app is about to suspend or go to the background, your method will be called before Corona's version, e.g.
applicationWillResignActive: and applicationDidEnterBackground:.
http://docs.coronalabs.com/native/enterprise/ios/CoronaDelegate.html
But this is just a guess. Hope it helps!
Edit:
I was thinking, something really simple you could do is catch it outside and present a "pause" screen, then just hide it when the application enters foreground.
So if you can't do that (for now), one other option is to save application state when the application is about to terminate, and then set UIApplicationExitsOnSuspend = true in your plist file. This will cause the application to exit instead of suspending, which will avoid any screenshots, effectively "hiding" the board, etc. The downfall is, the app will have to read the session state when it launches again... this is only useful if your application can be designed to actually exit without losing your state, and is quite honestly, a little extreme. That said, it may be the only way to effectively do what you're trying to do.
Other ideas would be to see if you can add a large black layer to the screen, even though the application is suspending; perhaps this will somehow trigger an internal screen update by natively setting setNeedsDisplay. Also, instead of modifying the alpha, you might consider temporarily removing all of your layers and see if that has a similar effect.
I have an app where I have 5 sets of animations that I'm storing in an array. The animations get picked to play randomly after a button touch. This is all working perfectly, however I noticed a bug when I quit the app and reopen immediately, I'll see my main view, then it'll jump to my second view that has the animation in it. (This shouldn't happen since you have to tap the main view in order for it to modally swap in the second view. If I interact with it everything works for a few seconds, then it closes with no crash log.
I finally realized that some of the objects must not be getting released fast enough, since if I close the app and wait three seconds, then reopen, everything executes fine.
I didn't want to put down code to show as this is more of a brainstorming question. I'd love any insight that could point me the right way. I changed a lot of my code to get rid of convenience methods and have all my variables defined and then released in my dealloc.
Is there a way to truly tell the app to kill everything on quit? It's not set to run in the background so this is a bit odd. Thanks for your help I'm still new to this and learning!
Alright, after working on this all weekend and doing more research comparing a barebones version of my app to my prerelease version, I traced memory leaks to the Flurry Analytics api that I am using. Apparently I was suffering from the same issue as the post here: App hangs on restart with latest Flurry SDK and ios4 . I resolved this by setting these optional methods to false, since they take extra time to send data after the app terminates, and depending on the connection it takes a few seconds.
FlurryAnalytics.h
/*
optional session settings that can be changed after start session
*/
+ (void)setSessionReportsOnCloseEnabled:(BOOL)sendSessionReportsOnClose; // default is YES
+ (void)setSessionReportsOnPauseEnabled:(BOOL)setSessionReportsOnPauseEnabled; // default is YES
Hope this helps anyone else who experienced something similar to me!
All apps can enter the background by default. Normally they do not do anything there, but they stay there in a frozen state and when you open them again, your program does not restart, it just picks up where it left off.
Anything that's set as an animation delegate might not get released, since it's retained for that purpose until the animation completes.
You can add an applicationDidEnterBackground: method to your app delegate to get informed when your app is going into the background, but exactly what you need to do depends on the design of your app. You can also add applicationWillEnterForeground: to do anything you need to do differently when restarting, as opposed to newly starting.
You might be able to force your animations to complete by starting a new animation with duration 0.0 (or very short if for some reason you can't do that).
If this happens only if your app goes to bkgnd and comes back AND you don't mind if the app restarts everytime it comes back then just put UIApplicationExitsOnSuspend in your app's plist. In all my cases where these and other bad things happen with apps going to and returning from bkgnd this helped.
While you might still see the app on the buttom when double tapping it is really stopped and will restart. Apps that show on the buttom do not always have to run or be stored in the bkgnd I learned.
ps. don't forget to set the value of UIApplicationExitsOnSuspend to YES
I have an app that imports data on start using Core Data. In this part of the app, I have disabled resuming (multitasking) by calling exit(0) in applicationDidEnterBackground when a flag is set. E.g.:
-(void)applicationDidEnterBackground:(UIApplication *)application {
if (allowResuming==NO){
NSLog(#"Terminating...");
exit(0);
}
}
If I then attempt to 'resume' the app (by pressing its icon) within 11 seconds of having pressed the Home button (and, therefore, exit(0) having been called), the app crashes. This doesn't happen when running through the debugger, but the crash logs suggest that it looks like the app is trying to resume the data import where it left off, which, of course, is not what I want.
Attempting to 'resume' the app again straight after this crash (i.e. within a second) is successful.
If I attempt to 'resume' the app after 11 seconds, it's fine.
I would be really grateful if anyone has any ideas and/or can point me in the right direction here.
I don't think you should be doing exit(0). To disable Multitasking, set the key UIApplicationExitsOnSuspend key in Info.plist to YES. For details, see the section Opting Out of Background Execution at
http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/CoreApplication/CoreApplication.html#//apple_ref/doc/uid/TP40007072-CH3-SW1.
To discard the partial work done when the app leaves foreground, add a listener for UIApplicationWillResignActiveNotification or UIApplicationDidEnterBackgroundNotification. In the handler method, you could do something like-
[self discardPartialWorkDone];
HTH,
Akshay
You should not use exit(0) like Akshay said. In addition to that Apple will probably reject your App, because Apps which consist of code which interrupt the App like this wont be approved.
In my Universal-App i have some issues where the app crashes. I could not reproduce the cause of the crash so i want at least make the app "save" so that it can restart again if it has crashed.
Problem is, if my app crashes, it can happen that it cannot be started again due to some messed up user defaults.
So, if i could delete my user defaults after my app has crashed while starting, the user could at least use the app furthermore.
So far for my goals. Now i only need to know how i can detect and save it, when my app has crashed during starting.
My first intention was to set a flag in user defaults when the app crashes and then ,if the flag is set, to reset the user defaults. But i don't know if - (void)applicationWillTerminate:(UIApplication *)application
will be called when my app crashes. And even if it is called. How can i detect if it crashed during starting?
Any suggestions would be welcome.
Greetings and thx in advance
Maverick1st
What about setting a flag every time your app starts up and unsetting it when it terminates normally? That way you know if it is already set when the app starts, it crashed last time.
One of the things about abnormal exit is that is going to be, well, abnormal. It's usually not a great idea to rely on being able to do anything sensible in such cases.
Instead of trying to set a flag when you crash, which will at best be unreliable, how about instead setting it when you start and then unsetting it when you exit normally? That way it'll be left set if you haven't cleaned things up and you'll know next time you start.
One thought... wrap your main starting code in your app delegate in a #Try #Catch block to handle the exception causing the crash. Perform any last minute code there (like setting your flag).
So I׳m trying to play some effects in my Cocos2D game using SimpleAudioEngine , but after I have added them my app crashes when it goes to background (multitasked).
I searched for this problem in the internet but all the solutions that I found didn't work for me. What I did find out is that this problem happens because my app is somehow trying to play sounds when backgrounded.
In console it shows me (which is the same error I found other people had):
sgx error (background gpu access not permitted):
And another thing, when I run my app on the simulator, or even on my device while debugging carefully (going line-by-line with XCode while the app is running) this doesn't happen.
I just had this issue. I resolved it by having a bool to check if the app is running or in background that I set to true when the app goes to foreground ( applicationWillEnterForeground ) and that I set to false when the app goes to background ( applicationDidEnterbackground ) . So using the bool you can tell if the app is in the background and if it is, I just exit out of drawView function in EAGLView (thus not doing any graphics rendering which was causing the error).
I am a very dodge programmer but that method has worked for me and I hope it works for someone else. I did not need to unload and reload my sounds or anything and my app now has Multitasking XD
I was experiencing this, on about 25% of the occasions that my application re-entered the foreground. Like you, when I removed the sounds, the problem went away. That is how I came across your question here.
I may have found a solution to this. I have made what appears to be an unrelated change, but the problem seems to have gone away. Now, when my app enters the background, I invalidate my main scheduled timer. When my app re-enters the foreground, I then re-schedule the timer (after reloading my sounds, which I completely shut down on entering background).
So far, the problem has not come back. I would be interested to know if this helps.
I just resolved this issue on my end. Here's what was wrong in my case and, from what I can tell from the other answers and comments on this page, many other people's case as well:
By default, when I started my project, CCDirector::sharedDirector()->pause(); and CCDirector::sharedDirector()->resume(); were both being called twice, once by (void)applicationWillResignActive:(UIApplication *) and (void)applicationDidBecomeActive:(UIApplication *) respectively in AppController.mm, and once by AppDelegate::applicationDidEnterBackground() and AppDelegate::applicationWillEnterForeground() respectively in AppDelegate.cpp.
Make absolutely sure that these methods are only being called once, in AppController.mm. In AppDelegate.cpp, instead make sure that you are calling CCDirector::sharedDirector()->stopAnimation(); in place of CCDirector::sharedDirector()->pause(); and CCDirector::sharedDirector()->startAnimation(); in place of CCDirector::sharedDirector()->resume();.
Hope that's helpful to anyone else stuck in this crappy situation!
Are you sure it's related to audio? "background gpu access" sounds like it's using OpenGL.
I had the same issue in my application and spent some 4 hours to find out. Going background was OK the first time, but crash application the second time. With a short error message related to OpenGL. I had the same questions: how audio can crash graphics. But it wasn't a question of audio, but a question of notifications...
I discovered that going foreground was creating 2 timers in my custom level meter class.
I had registered UIApplicationWillEnterForegroundNotification and UIApplicationWillResignActiveNotification. Then, going background invalidated only one, since I registered only on notification... That was it!
One need's count its notifications!