带有TabHost的选项卡式UI。标签图标不显示

Question

我刚刚完成了这个演练，一切都很好，但我的标签上没有图标。 Walkthrough我有手机用android 4.4。有可能android 4.4不再使用TabHost吗？

一些代码。

主要cs文件

namespace com.xamarin.example.tabhostwalkthrough
{
using System;

using Android.App;
using Android.Content;
using Android.Graphics.Drawables;
using Android.OS;
using Android.Widget;

[Activity(Label = "@string/app_name", MainLauncher = true, Icon = "@drawable/ic_launcher")]
public class TabHostWalkthrough : TabActivity
{
    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);
        SetContentView(Resource.Layout.Main);

        CreateTab(typeof(WhatsOnActivity), "whats_on", "What's On", Resource.Drawable.ic_tab_whats_on);
        CreateTab(typeof(SpeakersActivity), "speakers", "Speakers", Resource.Drawable.ic_tab_speakers);
        CreateTab(typeof(SessionsActivity), "sessions", "Sessions", Resource.Drawable.ic_tab_sessions);
        CreateTab(typeof(MyScheduleActivity), "my_schedule", "My Schedule", Resource.Drawable.ic_tab_my_schedule);
    }
    private void CreateTab(Type activityType, string tag, string label, int drawableId)
    {
        var intent = new Intent(this, activityType);
        intent.AddFlags(ActivityFlags.NewTask);

        var spec = TabHost.NewTabSpec(tag);
        var drawableIcon = Resources.GetDrawable(drawableId);
        spec.SetIndicator(label, drawableIcon);
        spec.SetContent(intent);

        TabHost.AddTab(spec);
    }
}

}

Tab xml文件

    <?xml version="1.0" encoding="utf-8"?>
    <selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/ic_tab_my_schedule_selected"     android:state_selected="true"/>
    <item android:drawable="@drawable/ic_tab_my_schedule_unselected"/>

.axml文件到主cs文件

<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <LinearLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="5dp">
        <TabWidget
        android:id="@android:id/tabs"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
        <FrameLayout
        android:id="@android:id/tabcontent"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:padding="5dp" />
    </LinearLayout>
</TabHost>