iOS PHPickerViewController不提供Exif/Meta-数据

Question

我正在尝试从我用PHPickerViewController获取的图像中读出一些元数据。

var config = PHPickerConfiguration()
self.phPicker = PHPickerViewController(configuration: config)
if let picker = self.phPicker {
    self.phPicker?.delegate = self
    self.present(picker, animated: true) {
        self.phPicker = nil
    }
}

但是访问这些数据的PHPickerResult.assetIdentifier总是为零。

extension ChatViewController: PHPickerViewControllerDelegate {
    func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
        dismiss(animated: true) {
            if results.isEmpty {
                return
            }
            assert(results.first!.assetIdentifier != nil)  // fails
        }
    }
}

Answer 1

诀窍是PHPickerViewController的正确配置。

var config = PHPickerConfiguration()  // WRONG!
let picker = PHPickerViewController(configuration: config)

根据文档，您必须使用PHPhotoLibrary。

A PHPhotoLibrary提供对用户照片库中照片、视频和相关内容的元数据和图像数据的访问，包括来自相机卷、iCloud共享、照片流、导入和从iTunes同步的内容。

因此，只需在构造函数中使用PHPhotoLibrary，一切都可以正常工作。

var config = PHPickerConfiguration(photoLibrary: PHPhotoLibrary.shared())  // CORRECT!
let picker = PHPickerViewController(configuration: config)