App Terminated due to Memory Pressure when using ZBar reader

Question

I'm using ZBar reader in my app for scanning QR Code. When I continuously open and close this scanner, the app terminated with message App Terminated due to Memory Pressure.

I searched over this and got an answer in which the same scenario that my app faces. ie, first time opening the scanner had a 1 second delay, second had a 2 second delay, third had a 5 second delay. and when going for fourth or fifth the app terminated.

But that answer is for UIImagePickerController. I'm using ZBar reader. Both are somewhat similar. I don't know how to modify my code to solve it.

Here is the code that I'm using,

codeReader = [ZBarReaderViewController new];
codeReader.readerDelegate=self;
codeReader.supportedOrientationsMask = ZBarOrientationMaskAll;
codeReader.showsCameraControls = NO;
codeReader.showsZBarControls=NO;
ZBarImageScanner *scanner = codeReader.scanner;
[scanner setSymbology: ZBAR_I25 config: ZBAR_CFG_ENABLE to: 0];
Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {
   AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
   if ([device hasTorch] || [device hasFlash]){
     [device lockForConfiguration:nil];
     [device setTorchMode:AVCaptureTorchModeOff];
     [device setFlashMode:AVCaptureFlashModeOff];
     [device unlockForConfiguration];
   }
}
[self.view.window.rootViewController presentViewController:codeReader animated:YES completion:nil];

codeReader.cameraOverlayView = overlayview;

How should I change it to solve the issue?

You can use the 'leaks' instrument to try and identify where you are leaking memory. The other thing you should do is see if you can create a single instance of a ZBar reader and the activiate/deactivate it rather than continually creating a new one as this is expensive in terms of time and memory. In one of my apps I am using ZXingObjC and this is the approach I take to make things faster — Paulw11, Apr 03 '14 at 05:19
Probably the easiest is to store in on a property of your app delegate and allocate it in your didFinishLaunching method. — Paulw11, Apr 03 '14 at 05:30

score 1 · Accepted Answer · answered Apr 03 '14 at 05:41

You can create a single instance of your ZBar reader and store it as a property on your app delegate or you can use the singleton approach that was suggested in the UIPickerController answer.

In your appDelegate.h

@property (strong,nonatomic) ZBarReaderViewController *zbarReaderVC;

In your appDidFinishLaunching in appDelegate.m

self.zbarReaderVC = [ZBarReaderViewController new];
self.zbarReaderVC.readerDelegate=self;
self.zbarReaderVC.supportedOrientationsMask = ZBarOrientationMaskAll;
self.zbarReaderVC.showsCameraControls = NO;
self.zbarReaderVC.showsZBarControls=NO;
ZBarImageScanner *scanner = self.zbarReaderVC.scanner;
[scanner setSymbology: ZBAR_I25 config: ZBAR_CFG_ENABLE to: 0];
Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {
   AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
   if ([device hasTorch] || [device hasFlash]){
     [device lockForConfiguration:nil];
     [device setTorchMode:AVCaptureTorchModeOff];
     [device setFlashMode:AVCaptureFlashModeOff];
     [device unlockForConfiguration];
   }
}

Then whenever you need the view

MyAppDelegate *d=[UIApplication sharedApplication].delegate;

ZBarReaderViewController codeReader=d.zbarReaderVC;

[self.view.window.rootViewController presentViewController:codeReader animated:YES completion:nil];

codeReader.cameraOverlayView = overlayview;

When you have finished with it remove it from the presenting view controller.

I haven't read through the docs of ZBar reader, but there is probably a method you need to call to start/stop it processing images even when it isn't presented. I know there is with ZXingObjC.

Thanks for the idea. I used the above code in viewdidload function that the view controller will be loaded only one time and the `imagePickerController didFinishPickingMediaWithInfo` should be there to get the image. Anyway the memory issue got fixed. — Nazik, Apr 03 '14 at 06:21

App Terminated due to Memory Pressure when using ZBar reader

1 Answers1