iOS Delegate method not called in NSObject class - objective-c

Question

I want to capture a picture from the camera with no preview.
Though I am able to do that with a UIViewController with the help of AVFoundation framework.
But now I have to do the same without the ViewController.
#Issue
When I trying to do the same with a NSObject class the AVCapturePhotoCaptureDelegate is not called.
TestingCamera.h
#import <AVFoundation/AVFoundation.h>
NS_ASSUME_NONNULL_BEGIN
#interface TestingCamera : NSObject <AVCapturePhotoCaptureDelegate> {
AVCaptureSession *captureSession;
AVCapturePhotoOutput *photoOutput;
AVCapturePhotoSettings *photoSetting;
AVCaptureConnection *captureConnection;
}
#property(nonatomic, assign) id <AVCapturePhotoCaptureDelegate> delegate;
- (void) takePictureWithNoPreviewFrontFacingCamera;
#end
NS_ASSUME_NONNULL_END
TestingCamera.m
#import "TestingCamera.h"
#implementation TestingCamera
- (void) initCaptureSession {
captureSession = [[AVCaptureSession alloc] init];
if([captureSession canSetSessionPreset: AVCaptureSessionPresetPhoto] ) {
[captureSession setSessionPreset:AVCaptureSessionPresetPhoto];
}
[captureSession startRunning];
}
-(void) setNewPhotoSetting {
photoSetting = [AVCapturePhotoSettings photoSettingsWithFormat:#{AVVideoCodecKey : AVVideoCodecTypeJPEG}];
[photoOutput setPhotoSettingsForSceneMonitoring:photoSetting];
}
-(void) takePictureWithNoPreviewFrontFacingCamera {
[self initCaptureSession];
[self initInputDevice:[self frontFacingCameraIfAvailable]];
[self initOuput];
[self setNewPhotoSetting];
captureConnection = nil;
for (AVCaptureConnection *connection in photoOutput.connections) {
for (AVCaptureInputPort *port in [connection inputPorts]) {
if ([[port mediaType] isEqual: AVMediaTypeVideo]) {
captureConnection = connection;
break;
}
}
if (captureConnection) {
break;
}
}
[photoOutput capturePhotoWithSettings:photoSetting delegate:self];
}
-(void) initInputDevice: (AVCaptureDevice *) inputDevice {
AVCaptureDeviceInput *deviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:inputDevice error:nil];
if ([captureSession canAddInput:deviceInput]) {
[captureSession addInput:deviceInput];
}
}
-(void) initOuput {
photoOutput = [[AVCapturePhotoOutput alloc] init];
if ([captureSession canAddOutput:photoOutput]) {
[captureSession addOutput:photoOutput];
}
}
-(AVCaptureDevice *) frontFacingCameraIfAvailable {
AVCaptureDeviceDiscoverySession *captureDeviceDiscoverySession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:#[AVCaptureDeviceTypeBuiltInWideAngleCamera] mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionFront];
NSArray *captureDevices = [captureDeviceDiscoverySession devices];
if (!captureDevices || !captureDevices[0]){
return [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
} else {
return captureDevices[0];
}
}
- (void)captureOutput:(AVCapturePhotoOutput *)output didFinishProcessingPhoto:(AVCapturePhoto *)photo error:(nullable NSError *)error
{
NSData *imageData = [photo fileDataRepresentation];
NSString *base64 = [imageData base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
NSLog(#"Encoded: %#", base64);
}
#end
I am calling the method from another ViewController like this
- (IBAction) testPicture:(id)sender {
TestingCamera *noPreviewCamera = [[TestingCamera alloc] init];
[noPreviewCamera takePictureWithNoPreviewFrontFacingCamera];
}