Tab 键未在 Xamarin 表单 iOS

如何解决Tab 键未在 Xamarin 表单 iOS

我在 xamarin 表单 iOS 平台中有一个 xamarin 表单网格和一个为该网格编写的自定义渲染器。并将BecomeFirstResposnder 应用到OnElementPropertyChanged 上的Customrenderer。添加了 UIKeyCommand "\t " 到 UIViewController。UpArrow、DownArrow、LeftArrow 除了 Tab 和 Shift+Tab 键之外，每个键都在监听。请帮助我。

//Xamarin Forms Grid 的自定义渲染器

protected override void OnElementPropertyChanged(object sender,PropertyChangedEventArgs e)
{
    base.OnElementPropertyChanged(sender,e);
    this.BecomeFirstResponder();
    if (this.KeyPageRenderer == null)
    {
        this.KeyPageRenderer = this.GetSfPageRenderer(this.GetControl());
        if (this.KeyPageRenderer != null)
        {
            UIKeyCommand KeyTab = UIKeyCommand.Create(new Nsstring("\t"),new ObjCRuntime.Selector("KeyRecV:"));
            this.KeyPageRenderer.AddKeyCommand(KeyTab);
        }
    }
}

internal UIViewController GetSfPageRenderer(UIView view)
{
    if (view != null)
    {
        var responder = (UIResponder)view;
        while (responder != null && !(responder is UIViewController))
        {
            responder = responder.NextResponder;
        }
        return responder as UIViewController;
    }
    return null;
}

public override bool CanBecomeFirstResponder
{
    get
    {
        return true;
    }
}
[Export("KeyRecV:")]
private void Excute(UIKeyCommand keyCommand)
{
    if ((keyCommand.Input as NSObject).Description == "\t")
    {

    }
}