如何在Xamarin forms IOS中实现类似android的文件浏览器

public interface IFileBrowser
{
    Task<string> PickFile();
}

[assembly: Dependency(typeof(FileBrowser_iOS))]
namespace YourNamespace.iOS
{
    public class FileBrowser_iOS : IFileBrowser
    {
        public Task<string> PickFile()
        {
            var tcs = new TaskCompletionSource<string>();

            var documentPicker = new UIDocumentPickerViewController(new[] { UTType.Item }, UIDocumentPickerMode.Open);
            documentPicker.DidPickDocument += (sender, e) =>
            {
                var securityUrl = e.Url;
                var fileManager = new NSFileManager();
                var fileUrl = fileManager.GetTemporaryDirectory().Append(securityUrl.LastPathComponent, false);
                fileManager.Move(securityUrl, fileUrl);

                tcs.SetResult(fileUrl.Path);
            };
            documentPicker.WasCancelled += (sender, e) =>
            {
                tcs.SetResult(null);
            };

            var viewController = UIApplication.SharedApplication.KeyWindow.RootViewController;
            viewController.PresentViewController(documentPicker, true, null);

            return tcs.Task;
        }
    }
}

private async void OpenFileBrowser()
{
    var fileBrowser = DependencyService.Get<IFileBrowser>();
    var filePath = await fileBrowser.PickFile();

    if (!string.IsNullOrEmpty(filePath))
    {
        // 处理选择的文件路径
    }
}