Metadata Recognition with AVFoundation

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface ViewController : UIViewController <AVCaptureMetadataOutputObjectsDelegate>

@end

#import "ViewController.h"
#import <AudioToolbox/AudioServices.h>

@implementation ViewController

- (void)viewDidAppear:(BOOL)animated {

    [super viewDidAppear:animated];

    NSError* error;

    AVCaptureSession* session = [[AVCaptureSession alloc] init];
    [session setSessionPreset:AVCaptureSessionPresetHigh];

    AVCaptureDevice* captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    AVCaptureDeviceInput* deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];
    if ([session canAddInput:deviceInput]) {
        [session addInput:deviceInput];
    }

    AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
    [previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

    CALayer *rootLayer = [[self view] layer];
    [rootLayer setMasksToBounds:YES];
    [previewLayer setFrame:CGRectMake(-70, 0, rootLayer.bounds.size.height, rootLayer.bounds.size.height)];
    [rootLayer insertSublayer:previewLayer atIndex:0];

    [session startRunning];

    AVCaptureMetadataOutput* output = [[AVCaptureMetadataOutput alloc] init];
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    if ([session canAddOutput:output]) {
        [session addOutput:output];
    }

    // add the desired metadata types here:
    output.metadataObjectTypes = @[ AVMetadataObjectTypeFace ];
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection {

    // handle output
}

@end