仅查看UIIMagePictureController中的视频

Question

因此，我创建了自己的UIImagePicker，当用户单击按钮时将显示该UIImagePicker。我已经做到了，所以这个图像选择器仅显示视频。但是，当我第一次显示它时，它仍然显示，相机胶卷，然后是照片，然后当我单击照片库时，那里只有视频，正如我期望的那样。

但是我怎么只会看视频。

就像在此屏幕上一样，我希望将相册标记为视频。

这是我的图像选择器控制器代码

/// Selector Controller used to pick a video
open class ImagePickerController : UIImagePickerController, TypedRowControllerType, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

    /// The row that pushed or presented this controller
    public var row: RowOf<URL>!

    /// A closure to be called when the controller disappears.
    public var onDismissCallback : ((UIViewController) -> ())?

    open override func viewDidLoad() {
        super.viewDidLoad()
        delegate = self
        mediaTypes = [kUTTypeMovie as String]
    }

    public func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        guard let videoURL = info[UIImagePickerControllerMediaURL] as? URL else {
            return
        }

        (row as? _VideoRow)?.videoURL = videoURL
        onDismissCallback?(self)
    }

    open func imagePickerControllerDidCancel(_ picker: UIImagePickerController){
        onDismissCallback?(self)
    }
}

这是我对源类型进行的布局

public struct VideoRowSourceTypes : OptionSet {

    public let rawValue: Int
    public var imagePickerControllerSourceTypeRawValue: Int { return self.rawValue >> 1 }

    public init(rawValue: Int) { self.rawValue = rawValue }
    init(_ sourceType: UIImagePickerController.SourceType) { self.init(rawValue: 1 << sourceType.rawValue) }

    public static let PhotoLibrary = VideoRowSourceTypes(.photoLibrary)
    public static let All: VideoRowSourceTypes = [PhotoLibrary]

}

所以我的问题是，当我转到imagePicker时，如何使其只显示视频，而不是单击相机胶卷然后选择视频？ 和 如何更改导航栏的标题以选择视频，因为此行代码不起作用

private func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
    viewController.navigationItem.title = "Choose Video"
}