How to add 'cancel' button to camera acquisition code? - objective-c

Question

I have this code which captures a barcode; it works fine, except on an iPad, if you can't/don't hold the iPad steady, it "tries until the cows come home" if you get my drift. I want to add a "cancel" button or figure out some way to cancel the method so I don't have to kill the app and start it again. Here is my code:
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection {
CGRect highlightViewRect = CGRectZero;
AVMetadataMachineReadableCodeObject *barCodeObject;
NSString *detectionString = nil;
NSArray *barCodeTypes = #[AVMetadataObjectTypeEAN13Code];
for (AVMetadataObject *metadata in metadataObjects) {
for (NSString *type in barCodeTypes) {
if ([metadata.type isEqualToString:type])
{
barCodeObject = (AVMetadataMachineReadableCodeObject *)[_prevLayer transformedMetadataObjectForMetadataObject:(AVMetadataMachineReadableCodeObject *)metadata];
highlightViewRect = barCodeObject.bounds;
detectionString = [(AVMetadataMachineReadableCodeObject *)metadata stringValue];
break;
}
}
if (detectionString != nil) {
_label.text = detectionString;
oISBNField.text = detectionString; // move detectionString to ISBN textbox
[_session stopRunning];
[_prevLayer removeFromSuperlayer];
[_label removeFromSuperview];
break;
}
else
_label.text = #"(none)";
}
}
Can someone please give me some help on this? I would really, really appreciate it! :D

Answer 1

Just create a cancel button and add it to the UIViewController's view.
When the button is pressed, stop the capture session and dismiss the presented view controller.
- (void)cancelButtonPressed:(id)sender {
[self.captureSession stopRunning]; //stop the capture session
[self.presentingViewController dismissViewControllerAnimated:YES completion:nil]; // dismiss the current view controller
}