public override void ViewDidLoad()
{
base.ViewDidLoad ();
var v1 = new UIView ();
v1.BackgroundColor = UIColor.Red;
this.View.AddSubview (v1);
v1.AlignTopAndLeading ("20", "20", v1.Superview);
v1.ConstrainWidthAndHeight ("40", "40");
// Perform any additional setup after loading the view, typically from a nib.
}