Xamarin.Forms Android custom ContentPage PageRenderer not rendering views - xamarin.android

Question

This doc explains how to create custom PageRenderer for Android, iOS etc. I tried as per docs but don't know why it's not working for Android. However it does works for iOS.
Shared ContentPage class:
public class SecondPage : ContentPage
{
public SecondPage()
{
Content = new StackLayout
{
Children = {
new Label { Text = "Hello ContentPage" }
}
};
}
}
Custom PageRenderer class for Android:
[assembly: ExportRenderer(typeof(SecondPage), typeof(SecondPageRenderer))]
namespace RenderFormsTest.Droid
{
public class SecondPageRenderer : PageRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<Page> e)
{
base.OnElementChanged(e);
if (e.OldElement != null || Element == null)
{
return;
}
InitView();
}
void InitView()
{
var context = Forms.Context;
string[] os = { "Android", "iOS", "Windows" };
var ll = new LinearLayout(context);
ll.LayoutParameters = new LayoutParams(LayoutParams.MatchParent, LayoutParams.MatchParent);
ll.SetBackgroundColor(Android.Graphics.Color.IndianRed);
var rg = new RadioGroup(context);
for (int index = 0; index < os.Length; index++)
{
rg.AddView(new RadioButton(context) { Text = os[index] });
}
ll.AddView(rg);
AddView(ll);
}
}
}
Can you please tell me what went wrong ?

Answer 1

I had similar problems. It seems the layout is incorrect. Try to set it in PageRenderer.OnLayout:
[assembly: ExportRenderer(typeof(SecondPage), typeof(SecondPageRenderer))]
namespace RenderFormsTest.Droid
{
protected Android.Views.View NativeView;
public class SecondPageRenderer : PageRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<Page> e)
{
base.OnElementChanged(e);
if (e.OldElement != null || Element == null)
{
if (Element == null)
NativeView = null;
return;
}
InitView();
}
void InitView()
{
var context = Forms.Context;
string[] os = { "Android", "iOS", "Windows" };
var ll = new LinearLayout(context);
ll.LayoutParameters = new LayoutParams(LayoutParams.MatchParent, LayoutParams.MatchParent);
ll.SetBackgroundColor(Android.Graphics.Color.IndianRed);
var rg = new RadioGroup(context);
for (int index = 0; index < os.Length; index++)
{
rg.AddView(new RadioButton(context) { Text = os[index] });
}
ll.AddView(rg);
AddView(ll);
NativeView = ll;
}
protected override void OnLayout(bool changed, int l, int t, int r, int b)
{
base.OnLayout(changed, l, t, r, b);
if ( NativeView != null )
{
var msw = MeasureSpec.MakeMeasureSpec(r - l, MeasureSpecMode.Exactly);
var msh = MeasureSpec.MakeMeasureSpec(b - t, MeasureSpecMode.Exactly);
NativeView.Measure(msw, msh);
NativeView.Layout(0, 0, r - l, b - t);
}
}
}
}