UIImagePickerController.swift

extension CameraViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    static let sourceType: UIImagePickerControllerSourceType = .photoLibrary
    
    static let imagePickerController: UIImagePickerController? = {
        if UIImagePickerController.isSourceTypeAvailable(sourceType) {
            let imagePickerController = UIImagePickerController()
            imagePickerController.sourceType = sourceType
            return imagePickerController
        } else {
            return nil
        }
    }()
    
    @IBAction func libraryButtonTouched(_ sender: UIButton) {
        presentImagePicker(allowingEditing: false)
    }
    
    func presentImagePicker(allowingEditing: Bool) {
        if let picker = CameraViewController.imagePickerController {
            picker.delegate = self
            self.present(picker, animated: true, completion: nil)
        }
    }
    
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        var image: UIImage?
        if info.keys.contains(UIImagePickerControllerEditedImage) {
            image = info[UIImagePickerControllerEditedImage] as? UIImage
        } else {
            image = info[UIImagePickerControllerOriginalImage] as? UIImage
        }
        // Use `image`
        self.dismiss(animated: true, completion: nil)
    }
    
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        self.dismiss(animated: true, completion: nil)
    }
}