[iOS] ScrollViewRenderer: clear the renderer (#4489)

On Dispose(), the Renderer is supposed to be cleared on the element.
That's taken care of by VisualElementRenderer`1.Dispose().
Unfortunately, ScrollViewRenderer doesn't inherit from it.

I find it strange that this never was triggered before the Shell, but
I'm learning to live surrounded by strange behaviors.

-fixes #4381

diff --git a/Xamarin.Forms.Platform.iOS/Renderers/ScrollViewRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/ScrollViewRenderer.cs
index 31bab55..47281d0 100644 (file)
--- a/Xamarin.Forms.Platform.iOS/Renderers/ScrollViewRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/ScrollViewRenderer.cs
@@ -160,6 +160,7 @@ namespace Xamarin.Forms.Platform.iOS
                                if (_packager == null)
                                        return;
 
+                               Element?.ClearValue(Platform.RendererProperty);
                                SetElement(null);
 
                                _packager.Dispose();