swift5如何在用户授予有限访问权限以选择某些照片后仅显示有限的照片库

Question

在 WWDC2020 中，引入了新的 PHPickerViewController 和新的 PHPhotoLibrary.authorizationStatus(limited)。但我遇到了以下问题：

1. 当用户点击一个按钮以显示苹果的多个图像选择器并将 requestAuthorization 显示为代码时：

    let requiredAccessLevel: PHAccessLevel = .readWrite
    PHPhotoLibrary.requestAuthorization(for: requiredAccessLevel) { (authorizationStatus) in
          switch authorizationStatus {
          case .authorized:
              DispatchQueue.main.async {
                  self.presentImagePicker()
               }
          case .limited:
              DispatchQueue.main.async {
                  self.presentImagePicker()
               }
          default:
              break
          }
   }
   

2. self.presentImagePicker() 函数：

    func presentImagePicker() {
    var configuration = PHPickerConfiguration(photoLibrary: .shared())
    configuration.filter = .images
    configuration.selectionLimit = self.imageCountMax - self.images.count
    let picker = PHPickerViewController(configuration: configuration)
    picker.delegate = self
   
    let accessLevel: PHAccessLevel = .readWrite
    let authorizationStatus = PHPhotoLibrary.authorizationStatus(for: accessLevel)
   
    switch authorizationStatus {
    case .authorized:
        DispatchQueue.main.async {
   
            self.present(picker, animated: true)
        }
    case .limited:
        DispatchQueue.main.async {
            // Here I don't know how to display only limited photo library to users (after user has selected some photos through the limited access)
        }
    default:
        break
    }
   

   }

我的问题：请看代码2，case .limited: DispatchQueue.main.async { }，我想我应该把有限的照片库放在这个块中，但我不知道如何只显示有限的照片库用户。

Answer 1

您可以将这个PHPhotoLibrary.shared().presentLimitedLibraryPicker(from: self) 方法用于.limited

DispatchQueue.main.async {
         // Here I don't know how to display only limited photo library to users (after user has selected some photos through the limited access)
        PHPhotoLibrary.shared().register(self)
        PHPhotoLibrary.shared().presentLimitedLibraryPicker(from: self)
     }

然后你必须使用委托方法来获取更新的图像。

func photoLibraryDidChange(_ changeInstance: PHChange) {
        let fetchOptions = PHFetchOptions()
        self.allPhotos = PHAsset.fetchAssets(with: .image, options: fetchOptions)
    }