Question

I’m working on an app that the user can select if he wants to scan a barcode or take a picture of something.
For taking a picture I’m using the UIImagePickerController as usual.
For scanning barcode I’m using the ZbarSDK 1.2 ZBarReaderViewController.

When taking a picture everything works perfect.
When scanning a barcode:
If you start the app and scan a barcode before taking a picture, it’s also works perfect.

But is you take a picture, and then go back and try to scan a barcode, the camera loses the auto-focus and it’s just impossible to scan a barcode.

To summarize:
Start -> Scan -> Auto focus working
Start -> Take Photo -> Back -> Scan -> Auto focus not working

This is how I initialize the barcode scanner:

-(ZBarReaderViewController *) barcodeScanner
{
    if (nil == _barcodeScanner)
    {
        _barcodeScanner = [ZBarReaderViewController new];
        _barcodeScanner.readerDelegate = self;
        _barcodeScanner.cameraMode = ZBarReaderControllerCameraModeSampling;
        _barcodeScanner.sourceType = UIImagePickerControllerSourceTypeCamera;
    }
    return _barcodeScanner;
}

Any ideas?

Answer 1

Before loading up ZBarReaderViewController make sure you release UIImagePickerController, and before you load up UIImagePickerController make sure you release ZBarReaderViewController.

It took me days to figure out why i kept losing the ability to focus, and turns out that i wasn’t releasing things. For others stumbling onto this answer… You can only have 1 AVCaptureSession at a time otherwise things get screwy and you lose the ability to focus. ZBarReaderViewController uses AVCaptureSession so make sure you release it before you initialize a new AVCaptureSession.