Easily trigger the camera and take a picture with completion.

CameraManager.swift

class CameraManager: NSObject {
    static let shared: CameraManager = {
        let instance = CameraManager()
        return instance
    }()
    private var completions = [((UIImage?) -> Void, UIImagePickerController)]()
    
    @discardableResult
    func present(animated: Bool = true, on viewController: UIViewController? = nil, with completion: @escaping (UIImage?) -> Void) -> UIViewController? {
        guard let vc = viewController ?? UIApplication.shared.keyWindow?.rootViewController else {
            print("CameraManager error: rootViewController is not in the window hierarchy")
            return nil
        }
        guard UIImagePickerController.isSourceTypeAvailable(.camera) else {
            print("CameraManager error: Device does not supported")
            return nil
        }
        let pickerController = UIImagePickerController()
        pickerController.delegate = self
        pickerController.sourceType = .camera
        
        completions.append((completion, pickerController))
        vc.present(pickerController, animated: animated, completion: nil)
        return vc
    }
}

extension CameraManager: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        let completion = completions.first { $0.1 == picker }
        let image = info[UIImagePickerControllerOriginalImage] as? UIImage
        completion?.0(image)
    }
    
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        let completion = completions.first { $0.1 == picker }
        completion?.0(nil)
        completions.removeAll(where: { $0.1 == completion?.1})
    }
}