dismissViewControllerAnimated doesn't dismiss using ZbarSDK qr code reader - objective-c

Question

I'm using the zbarSDK QR code reader http://zbar.sourceforge.net/iphone/sdkdoc/
The SDK is very great but i encountered a little problem. I need the user to visualize a view before to start scanning (containing information about how to scan), than him press a button which made the scan start (showing the camera) and when the qr code has been scanned to Segue to another View showing something linked to the specific qr code.
I've done this, but it goes all well when i frame the qr code after starting the scan, but not if when i start the scan the qr code is already framed in the videocamera view.
When i start scan i do this
-(IBAction)StartScan:(id) sender
{
ZBarReaderViewController *reader = [ZBarReaderViewController new];
reader.readerDelegate = self;
reader.readerView.torchMode = 0;
ZBarImageScanner *scanner = reader.scanner;
// present and release the controller
[self presentModalViewController: reader
animated: YES];
[reader release];
}
using
[self presentModalViewController: reader
animated: YES];
to show the videocamera and scan the qr code.
and then when the qr code has been scanned i do this:
- (void) imagePickerController: (UIImagePickerController*) reader didFinishPickingMediaWithInfo: (NSDictionary*) info
{
id<NSFastEnumeration> results = [info objectForKey: ZBarReaderControllerResults];
ZBarSymbol *symbol = nil;
for(symbol in results)
hiddenData=[NSString stringWithString:symbol.data];
[reader dismissViewControllerAnimated:YES completion:^{ NSLog(#"Test"); }];
[self performSegueWithIdentifier:#"aDettaglioOpera" sender:self];
}
dismissing the camera view with
[reader dismissViewControllerAnimated:YES completion:^{ NSLog(#"Test"); }];
and presenting the view linked to the following segue.
Now all goes well if a point the camera to a point where there is not the qrcode and then point it to the qrcocde, instead if when i start scan i have already a qr code in the frame of the camera the imagePickerController get executed (i checked) but the dismissViewControllerAnimated:YES doesn't dismiss anything and doesn't execute the block after "completion" (which is instead correctly executed and nslogging "test")
What's the problem? The presentModalViewController has not the time it needs to allow the dismissViewControllerAnimated to function? And if the problem is this how can i avoid it?

Answer 1

I had the same problem and found a work around for this.
Set scanCrop property in reader as below before presentViewController and set it back back to default (0, 0, 1, 1) after 1 second. It works!!!
reader.scanCrop = CGRectMake(0, 0, 0.5, 0.5);
[self performSelector:#selector(changeScanCrop) withObject:nil afterDelay:1.0];
-(void)changeScanCrop {
reader.scanCrop = CGRectMake(0, 0, 1, 1);
}