AVFoundation (Objective-C, iOS 16): captureOutput not called

Question

I have a problem with captureOutput method not being called during the session. I tried adding NSLog to it but it seems that method is never called. Moreover, I tried searching for the solution, but didn't find any.

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

@interface Cam : NSObject <AVCaptureVideoDataOutputSampleBufferDelegate>
-(void)captureOutput:(AVCaptureOutput *)output
       didOutputSampleBuffer:(CMSampleBufferRef)buffer
       fromConnection:(AVCaptureConnection *)connection;
@end

@interface Cam ()
{
}

-(BOOL)start: (int)deviceIndex;
-(void)stop;
-(NSData *)getFrame;
@end

@implementation Cam

Cam *cam;
CVImageBufferRef head;
AVCaptureSession *session;
int count;

-(id)init
{
    self = [super init];
    head = nil;
    count = 0;
    return self;
}

-(void)dealloc
{
    @synchronized (self)
    {
        if (head != nil)
        {
            CFRelease(head);
        }
    }
}

-(BOOL)start:(int)deviceIndex
{
    int index;
    NSArray *devices;
    AVCaptureDeviceDiscoverySession *discoverySession;

    AVCaptureDevice *device;
    AVCaptureDeviceInput *input;
    AVCaptureVideoDataOutput *output;
    NSError *error;
    dispatch_queue_t queue;

    session = [[AVCaptureSession alloc] init];
    session.sessionPreset = AVCaptureSessionPresetMedium;

    discoverySession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInWideAngleCamera]
                                                        mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionUnspecified];
    devices = discoverySession.devices;
    index = deviceIndex;

    if (index < 0 || index >= [devices count])
    {
        log_debug("* Failed to open device (%d)\n", index);
        return NO;
    }

    device = devices[index];
    input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];

    if (!input)
    {
        log_debug("* Failed to capture input (%s)\n", [error.localizedDescription UTF8String]);
        return NO;
    }

    [session addInput:input];
    output = [[AVCaptureVideoDataOutput alloc] init];
    [session addOutput:output];

    queue = dispatch_queue_create("cam_queue", NULL);
    [output setAlwaysDiscardsLateVideoFrames:YES];
    [output setVideoSettings:@{(NSString *)kCVPixelBufferPixelFormatTypeKey:@(kCVPixelFormatType_32BGRA)}];
    [output setSampleBufferDelegate:self queue:queue];
    [session startRunning];

    return YES;
}

-(void)stop
{
    [session stopRunning];
}

-(NSData *)getFrame
{
    int timer;

    CIImage *ciImage;
    CIContext *temporaryContext;
    CGImageRef videoImage;
    UIImage *uiImage;
    NSData *frame;

    for (timer = 0; timer < 500; timer++)
    {
        if (count > 5)
        {
            break;
        }

        usleep(10000);
    }

    @synchronized (self)
    {
        if (head == nil)
        {
            log_debug("* Head is somehow nil (count: %d)\n", count);
            return nil;
        }

        ciImage = [[CIImage imageWithCVPixelBuffer:head] imageByApplyingOrientation:6];
        temporaryContext = [CIContext contextWithOptions:nil];
        videoImage = [temporaryContext createCGImage:ciImage fromRect:CGRectMake(0, 0,
                                        CVPixelBufferGetHeight(head),
                                        CVPixelBufferGetWidth(head))];
        uiImage = [[UIImage alloc] initWithCGImage:videoImage];
        frame = UIImageJPEGRepresentation(uiImage, 1.0);
        CGImageRelease(videoImage);

        return frame;
    }

    return nil;
}

-(void)captureOutput:(AVCaptureOutput *)output
       didOutputSampleBuffer:(CMSampleBufferRef)buffer
       fromConnection:(AVCaptureConnection *)connection
{
    CVImageBufferRef frame;
    CVImageBufferRef prev;

    frame = CMSampleBufferGetImageBuffer(buffer);
    CFRetain(frame);

    @synchronized (self)
    {
        prev = head;
        head = frame;
        count++;
    }

    if (prev != nil)
    {
        CFRelease(prev);
    }
}

@end

So, what I do is basically:

...
NSData *frame;

@autoreleasepool
{
    cam = [[Cam alloc] init];

    if ([cam start:camID])
    {
        frame = [cam getFrame];
        if (frame == nil)
            log_debug("* Frame is somehow nil?\n");
    }
    else
    {
        cam = nil;
    }
}
...

As a result I get * Frame is somehow nil? and * Head is somehow nil (count: 0)

I don't know what else I can do or fix. Please help me with this issue.

Thanks in advance