Integrating ZBar reader in project: creating custom viewcontroller

I have added this code to my project. It works fine, create and shows and instance of ZBarReaderViewController from the current view.

However I would like to be able to define a custom region of my current view controller and show ZBarReaderViewController inside that region whilst still showing my "previous/other" view. The code below show the view controller in full screen mode.

On interface builder I can only add UIViews in an existing ViewController and hence I am unable to associate the custom view region to ZBarReaderViewController.

The only thing I can do is to associate it to a ZBarReaderView instance but, as ZBarReaderViewController is a closed source (I can see only the header files on the ZBar reader project I am using) I am unable to modify the behaviour.

How can I solve this?

(IBAction)startScanning:(id)sender {

    NSLog(@"Scanning..");
    resultTextView.text = @"Scanning..";

    ZBarReaderViewController *codeReader = [ZBarReaderViewController new];
    codeReader.readerDelegate=self;
    codeReader.supportedOrientationsMask = ZBarOrientationMaskAll;

    ZBarImageScanner *scanner = codeReader.scanner;
    [scanner setSymbology: ZBAR_I25 config: ZBAR_CFG_ENABLE to: 0];

    [self presentViewController:codeReader animated:YES completion:nil];
}

Solution

So here is an example for a scanner view controller. I used storyboard to create the view, but you can do it also programatically or using regular nib.

First, create your view (let's say in a storyboard) and place a UIView inside it, where you would like the scanner to be shown.

Now, let's take a look on the view controller (please see comments inside it):

#import <AVFoundation/AVFoundation.h>
#import "ScannerViewController.h"

@interface ScannerViewController () <AVCaptureMetadataOutputObjectsDelegate>

// UI
@property (weak, nonatomic) IBOutlet UIView *viewPreview; // Connect it to the view you created in the storyboard, for the scanner preview

// Video
@property (nonatomic, strong) AVCaptureSession *captureSession;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;
@property (nonatomic, strong) AVAudioPlayer *audioPlayer;
@property (nonatomic, strong) AVCaptureSession *flashLightSession;
@property (nonatomic) BOOL isReading;

@end

@implementation ScannerViewController

- (void)viewDidLoad
{
     [super viewDidLoad];

     // Initially make the captureSession object nil.
     _captureSession = nil;

    // Set the initial value of the flag to NO.
    _isReading = NO;
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    [self startStopReading:nil];
}

- (IBAction)startStopReading:(id)sender
{
    if (!_isReading) {
        [self startReading];
    }
    else {
        // In this case the app is currently reading a QR code and it should stop doing so.
        [self stopReading];

    }

    // Set to the flag the exact opposite value of the one that currently has.
    _isReading = !_isReading;
}

#pragma mark - Private

- (BOOL)startReading
{
    NSError *error;

    // Get an instance of the AVCaptureDevice class to initialize a device object and provide the video
    // as the media type parameter.
    AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    // Get an instance of the AVCaptureDeviceInput class using the previous device object.
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];

    if (!input) {
        // If any error occurs, simply log the description of it and don't continue any more.
        NSLog(@"%@", [error localizedDescription]);
        return NO;
    }

    // Initialize the captureSession object.
    _captureSession = [[AVCaptureSession alloc] init];
    // Set the input device on the capture session.
    [_captureSession addInput:input];

    // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session.
    AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
    [_captureSession addOutput:captureMetadataOutput];

    // Create a new serial dispatch queue.
    dispatch_queue_t dispatchQueue;
    dispatchQueue = dispatch_queue_create("myQueue", NULL);
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];
    [captureMetadataOutput setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]]; // Add all the types you need, currently it is just QR code

    // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
    _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];
    [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [_videoPreviewLayer setFrame:_viewPreview.layer.bounds];
    [_viewPreview.layer addSublayer:_videoPreviewLayer];

    // Start video capture.
    [_captureSession startRunning];

    return YES;
}

- (void)stopReading
{
    // Stop video capture and make the capture session object nil.
    [_captureSession stopRunning];
    _captureSession = nil;

    // Remove the video preview layer from the viewPreview view's layer.
    [_videoPreviewLayer removeFromSuperlayer];
}

#pragma mark - AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
   // Check if the metadataObjects array is not nil and it contains at least one object.
   if (metadataObjects != nil && [metadataObjects count] > 0) {

        [self performSelectorOnMainThread:@selector(stopReading) withObject:nil waitUntilDone:NO];

        _isReading = NO;

        // If the audio player is not nil, then play the sound effect.
        if (_audioPlayer) {
            [_audioPlayer play];
        }

        // This was my result, but you can search the metadataObjects array for what you need exactly
        NSString *code = [(AVMetadataMachineReadableCodeObject *)[metadataObjects objectAtIndex:0] stringValue];

    }

}