Protocol and extension for handling the presentation of image picker controllers and selection of media

ImagePickerHandler.swift

// Since we are unable to extend ObjC protocols in swift, we wrap this around a custom NSObject subclass
// that deals exclusive with handling the image picker delegate methods and chaining the response down to
// the MediaPickerPresenter conforming delegate

class ImagePickerHandler: NSObject, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    var delegate: MediaPickerPresenter?
    let sourceType: UIImagePickerControllerSourceType
    let picker = UIImagePickerController()
    
    init(sourceType: UIImagePickerControllerSourceType) {
        self.sourceType = sourceType
        super.init()
        self.picker.delegate = self
    }
    
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        if let mediaType = info[UIImagePickerControllerMediaType] as? String {
            switch mediaType {
            case String(kUTTypeImage):
                if let selectedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
                    self.delegate?.didSelectFromMediaPicker(withImage: selectedImage)
                }
            case String(kUTTypeImage), String(kUTTypeMovie), String(kUTTypeVideo):
                if let selectedMediaURL = info[UIImagePickerControllerMediaURL] as? NSURL {
                    self.delegate?.didSelectFromMediaPicker(withMediaUrl: selectedMediaURL)
                }
            default:
                break
            }
        }
        picker.dismiss(animated: true, completion: nil)
    }
    
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        picker.dismiss(animated: true, completion: nil)
    }
    
}

MediaPickerPresenter.swift

protocol MediaPickerPresenter {
    var imagePickerHandler: ImagePickerHandler { get set }
    func presentMediaPicker(fromController controller: UIViewController, sourceType: UIImagePickerControllerSourceType)
    func didSelectFromMediaPicker(withImage image: UIImage)
    func didSelectFromMediaPicker(withMediaUrl mediaUrl: NSURL)
}

extension MediaPickerPresenter {
    func presentMediaPicker(fromController controller: UIViewController, sourceType: UIImagePickerControllerSourceType) {
        imagePickerHandler.delegate = self
        controller.present(imagePickerHandler.picker, animated: true, completion: nil)
    }
    
}

PresenterViewController.swift

class PresenterViewController: UIViewController, MediaPickerPresenter {

    var imagePickerHandler = ImagePickerHandler(sourceType: .photoLibrary) 
  
    func presentPicker() {
        self.presentMediaPicker(fromController: self)
    }
  
    func didSelectFromMediaPicker(withImage image: UIImage) {
        // ...
    }
    
    func didSelectFromMediaPicker(withMediaUrl mediaUrl: NSURL) {        
        // ...
    }
}

Hi, good solution, but don't assign type sourceType.

Hi, good solution, but don't assign type sourceType.

Could you explain why?