从iOS 11摄像机卷访问HEIC和DNG图片

我正在通过iOS 11应用程序（用Swift编写）访问原始HEIC和DNG文件；根据Apple开发者的文档，要访问原始文件，只需设置

imagePicker.imageExportPreset=UIImagePickerController.ImageURLExportPreset.current

，但在

UIImagePickerController.InfoKey.imageURL

上，我仍然可以得到指向JPEG文件的URL；我知道choosen图片是HEIC和DNG，因为在Mac photo app上导出为原始图片时，我会得到原始文件格式

这是我使用的完整代码：

@IBAction func openRoll(_ sender: Any) {
    if UIImagePickerController.isSourceTypeAvailable(.photoLibrary) {
        let imagePicker = UIImagePickerController()
        imagePicker.delegate = self
        imagePicker.sourceType = .photoLibrary
        imagePicker.allowsEditing = false
        imagePicker.imageExportPreset = .current
        self.present(imagePicker, animated: true, completion: nil)
    }
}

代表：

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    let image = info[UIImagePickerController.InfoKey.originalImage] as! UIImage

    let path = info[UIImagePickerController.InfoKey.imageURL] as! NSURL
    NSLog("URL: \(path.absoluteString)")
    NSLog("Export: \(picker.imageExportPreset.rawValue)")
    dismiss(animated:true, completion: nil)
    // ...code to use the image!
}

非常感谢您的帮助、建议和工作片段