Question

我有一个独立的类，可以使用UIImagePickerController从相机/照片库中获取图像。

我似乎无法弄清楚为什么不调用didFinishPickingMediaWithInfo或imagePickerControllerDidCancel方法..？我意识到这个问题已被多次询问，但我无法弄明白......我知道所有的方法名称都是正确的。

我已在info.plist中正确设置了以下所有内容：

隐私权 - 媒体库使用说明
隐私 - 照片库使用说明
隐私 - 照片库使用说明

import UIKit

class ImagePickerService: NSObject, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

  fileprivate var completion: ((UIImage) -> ())
  fileprivate var imagePicker: UIImagePickerController

  init(completion: @escaping ((UIImage) -> ())) {
    self.completion = completion
    self.imagePicker = UIImagePickerController()
    super.init()
    imagePicker.delegate = self
  }

  func show(from viewController: UIViewController) {
    showAlert(from: viewController)
  }

  fileprivate func showAlert(from viewController: UIViewController) {
    let alert = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
    alert.addAction(UIAlertAction(title: "Take a photo", style: .default) { _ in
      self.openCamera(from: viewController)
    })
    alert.addAction(UIAlertAction(title: "Choose from library", style: .default) { _ in
      self.openGallery(from: viewController)
    })
    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
    viewController.present(alert, animated: true, completion: nil)
  }

  // MARK: Image Picker

  fileprivate func openCamera(from viewController: UIViewController) {
    guard UIImagePickerController.isSourceTypeAvailable(.camera) else {
      viewController.showOKAlert(title: "Error!", message: "No camera available")
      return
    }
    showImagePicker(withSource: .camera, from: viewController)
  }

  fileprivate func openGallery(from viewController: UIViewController) {
    showImagePicker(withSource: .photoLibrary, from: viewController)
  }

  fileprivate func showImagePicker(withSource source: UIImagePickerControllerSourceType, from viewController: UIViewController) {
    imagePicker.sourceType = source
    viewController.present(imagePicker, animated: true, completion: nil)
  }

}

extension ImagePickerService {

  func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
    guard let image = info[UIImagePickerControllerEditedImage] as? UIImage else {
      return
    }
    completion(image)
    picker.dismiss(animated: true, completion: nil)
  }

  func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
    picker.dismiss(animated: true, completion: nil)
  }

}

修改问题是我没有在实例化时创建对ImagePickerService的强引用，并且在调用委托方法之前它是自动发布的。

Answer 1

问题出现在以下代码段中：

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
    guard let image = info[UIImagePickerControllerEditedImage] as? UIImage else {
      return
    }
    completion(image)
    picker.dismiss(animated: true, completion: nil)
}

您希望始终有经过编辑的图像，但照片库中的所有照片可能并非如此。当UIImagePickerControllerOriginalImage返回info[UIImagePickerControllerEditedImage]时，请尝试使用nil密钥。

如果首先没有调用这些方法，则需要确保对ImagePickerService实例有强引用。

例如，此代码有效：

class ViewController: UIViewController {

    var picker: ImagePickerService?

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) { [weak self] in
            guard let `self` = self else { return }
            self.picker = ImagePickerService() { (image) in
                print(image)
            }
            self.picker?.show(from: self)
        }
    }

}

Answer 2

尝试创建ImagePickerService类的单例：

static let shared = ImagePickerService()

创建单例后，将维护对服务对象的引用，并且不会释放它。

在init（）中设置委托并创建一个显示ImagePicker的方法。

func pickMedia(from: UIViewController?,didPickMedia: ((UIImage) -> ())?){      
            //self.openCamera()
            //or
            //self.openGallery()
}

从单身人士中你可以将其呈现为：

  ImagePickerService.shared.pickMedia(from: self) { (image) in

  }

UIImagePickerControllerDelegate未调用

2 个答案: