How to I handle keyboard appearance/disappearance in xamarin.forms - xamarin.forms

Question

I have a topmost grid
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="120"/>
<RowDefinition Height="1"/>
<RowDefinition Height="5"/>
<RowDefinition Height="35"/>
<RowDefinition Height="5"/>
</Grid.RowDefinitions>
in my page.
How could I have * row to adjust it's height to respect the presence or absence of on screen keyboard?
So that the content in the row 0 shrinks as the keyboard appears.
Or, at the very least how could I detect keyboard shows up
on an Editor?
I have a custom renderer for that Editor already
so stuffing extra platform specific code can be done swiftly.

Answer 1

You can control Grid row size only manually. Editor.Focused and Editor.Unfocused is what you're looking for.
But you can combine it with event Triggers (http://developer.xamarin.com/guides/cross-platform/xamarin-forms/working-with/triggers/):
<EventTrigger Event="Focused">
<local:FocusedTriggerAction />
</EventTrigger>
public class FocusedTriggerAction : TriggerAction<Editor>
{
protected override void Invoke (Editor editor)
{
yourRow.Height = new GridLength(100);
}
}

Answer 2

For now I've adapted the solution found here
http://www.gooorack.com/2013/08/28/xamarin-moving-the-view-on-keyboard-show/
private UIView activeview; // Controller that activated the keyboard
/// <summary>
/// Initializes a new instance of the <see cref="ExtendedEditorRenderer"/> class.
/// </summary>
public ExtendedEditorRenderer ()
{
NSNotificationCenter.DefaultCenter.AddObserver(UIKeyboard.DidShowNotification,KeyBoardUpNotification);
NSNotificationCenter.DefaultCenter.AddObserver(UIKeyboard.WillHideNotification,KeyBoardDownNotification);
}
public void Dispose()
{
NSNotificationCenter.DefaultCenter.RemoveObserver(UIKeyboard.DidShowNotification);
NSNotificationCenter.DefaultCenter.RemoveObserver(UIKeyboard.WillHideNotification);
base.Dispose();
}
private void KeyBoardDownNotification(NSNotification notification)
{
try
{
var view = (ExtendedEditor)Element;
if (view.KeyboardListener != null)
{
Size s = new Size(0, 0);
view.KeyboardListener.keyboardSizeChangedTo(s);
}
}
catch (Exception ex)
{
//Debug.WriteLine("dcaught {0}", ex);
}
}
private void KeyBoardUpNotification(NSNotification notification)
{
try
{
// get the keyboard size
CGRect r = UIKeyboard.BoundsFromNotification(notification);
Size s = new Size(r.Size.Width, r.Size.Height);
var v = (ExtendedEditor)Element;
v.KeyboardListener.keyboardSizeChangedTo(s);
}
catch(Exception ex) {
//Debug.WriteLine("scaught {0}", ex);
}
}
shared platform "independent" code:
public interface IKeyboardListener
{
void keyboardSizeChangedTo(Size s);
}
public class ExtendedEditor : Editor ...
{