Any use of OpenGL ES when the application is in the background will cause the application to be killed. What are you trying to do in GPUImage when your application is going to the background and getting killed?

I noticed this happens when the camera preview is active when the home or lock buttons are pressed.

Can you solve it ? I meet it too, can you help me?

I have this problem too. I tried to register for a notification to run "stopCameraCapture" when applicationWillResignActive gets called in the appDelegate, but the crash still occurs. Stopping the camera via a button action before moving the app into the background works though, however it requires the user to stop the camera himself.

update*
it doesn't crash anymore when I run "pauseCameraCapture" when applicationWillResignActive gets called. Similarly, run "resumeCameraCapture" when your app enters foreground to use the camera again.

I'm having the same crash issue. Pausing the capture when we applicationWillResignActive works if the user pressed the home button, but not the power button. It also doesn't crash if I place a breakpoint on applicationWillResignActive.

Calling [pauseCameraCapture] seems to resolve the issue for me.

Well the problem is that if I call stopCaptureStream I get an exception.
The problem is that the willResign method ends BEFORE the stream has stoped,
this also may cause the GL-thread to get a frame and process it...
thats why its all good when u use the debugger.

My fix:
U need to add an observer for AVCaptureSessionDidStopRunningNotification.
Instead of calling pause, we stop the capture
and wait in willResign until the onStop event has been fired.
then we call glfinish()!
Thats what the apple docu says. It wait until every GL thing is done so far
smth like this

- (void) onVideoStop
{
    DLog(@"video stoped");
    waitingForStreamToEnd = NO;
}

....

-(void) goToSleep
{
    waitingForStreamToEnd = YES;
    [stillCamera pauseCameraCapture];
    stillCamera = nil;  // I use ARC this calls release, and the deallc calls stopCameraCapture
    while(waitingForStreamToEnd)
    {

    }
     glFinish();
}

I hope this helps

@j455 Interesting. That seems like a sound idea. I take it that this seems to fix the problem reliably, or are you still evaluating?

Tomorrow I will evaluate it depply...but atm I must say it fixes it for me...
Pls note that I kill the stillcam as well.
I only keep my texutres, that what the apple docu surgests

If it works... one can simply add a method into the Framework to wait for that thing to happend

From: Cameron Perry
Sent: Wednesday, November 07, 2012 5:51 PM
To: BradLarson/GPUImage
Cc: J455
Subject: Re: [GPUImage] Crash when app goes in background. (#197)

@j455 Interesting. That seems like a sound idea. I take it that this seems to fix the problem reliably, or are you still evaluating?

—
Reply to this email directly or view it on GitHub.

Nvm... doenst work neither

The only thing that really makes this "stable" is to add these two lines at the end of the will resign
sleep(2);
glFinish();

I think the problem is that

[videoOutput setSampleBufferDelegate:nil queue:dispatch_get_main_queue()];
[audioOutput setSampleBufferDelegate:nil queue:dispatch_get_main_queue()];

Use the main queue but it gets no time to complete during the resign method or smth...
fact is if I dont add the sleep
the destructor seems to be executed AFTER the will resign method was left.
And that (ofc) leads to an error...
As I just started with iOS I am not cool enough to fix that :(
but one of you nerdy hackers sure will be:D

Hi folks, just to summarize the findings here:

• OpenGL may not be used when your app is in the background, so:
• You should listen for the UIApplicationWillResignActiveNotification and UIApplicationWillEnterForegroundNotification notifications while your camera view is onscreen.
• When your app is backgrounded, you need to stop GPUImage. Calling stopCameraCapture is asynchronous and doesn't stop using OpenGL immediately. This means that iOS will still kill your app sometimes, in spite of your best efforts to stop the camera in resignActive.
• calling pauseCameraCapture is synchronous (it appears). Listening for resignActive and pausing camera capture reliably fixes the crash on the home button and power button press (for me at least.). The only trick is that you need to call resumeCameraCapture when your app returns to the foreground. Calling startCameraCapture when paused seems to have no effect.

Hi

Ye that sounds reasonable. one more thing is, when u pull down the status thing. The OS overall thing that shows the weather and latest feeds, Does your fix do the trick for that too ?

-Cheers,
Kastor

Why "resign active" and not "did enter background"?

didEnterBackground would be called after the app is in the background, willResignActive is called while the app is in the foreground, but will enter the background.

I know it's been a couple years since this is was first filed, but I'm still experiencing this exact problem.
I followed the advice and I'm running the following:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willResignActive) name:UIApplicationWillResignActiveNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didBecomeActive) name:UIApplicationDidBecomeActiveNotification object:nil];`
...
- (void)willResignActive {
    [self.camera pauseCameraCapture];
}
- (void)didBecomeActive {
    [self.camera resumeCameraCapture];
}

Anyone have any thoughts?

I am having the same issue as emmasteimann. This is happening for me on GPUImage 0.1.4 even with the proposed fix.

I recommend adding an observer for UIApplicationDidEnterBackgroundNotification as this allows the camera to still operate when double tapping the home button so the smaller app preview still shows the camera feed then pauses when actually put in the background by swapping to a different app.

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willResignActive) name:UIApplicationDidEnterBackgroundNotification object:nil];

I was able to solve this:

- (void)observeGlobalNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onApplicationWillResignActive) name:UIApplicationWillResignActiveNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onApplicationDidBecomeActive) name:UIApplicationDidBecomeActiveNotification object:nil];
}

- (void)unobserveGlobalNotifications
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillResignActiveNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidBecomeActiveNotification object:nil];
}

- (void)onApplicationWillResignActive
{     
    [self.camera pauseCameraCapture];
    [self.camera stopCameraCapture];

    runSynchronouslyOnVideoProcessingQueue(^{
        glFinish();
    });
}

- (void)onApplicationDidBecomeActive
{
    [self.camera resumeCameraCapture];
    [self.camera startCameraCapture];
}

Thanks @henryl that for sure fixed it. Much appreciated! :-)

https://developer.apple.com/library/content/qa/qa1766/_index.html

I do like this,but it also crash sometimes when app enterbackground in older iOS devices. self.movie is a instance of GPUImageMovie.

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willResignActive) name:UIApplicationWillResignActiveNotification object:nil];

• (void)willResignActive {
  [self.movie cancelProcessing];
  }