public override void ViewDidLoad()
{
base.ViewDidLoad ();
View.BackgroundColor = UIColor.White;
_fbShare = new UIButton(UIButtonType.RoundedRect);
_fbShare.TouchUpInside += OnLoginClicked;
_fbShare.SetTitle("Share in Facebook", UIControlState.Normal);
_fbShare.SetTitleColor (UIColor.White, UIControlState.Normal);
_fbShare.BackgroundColor = UIColor.Blue;
_fbShare.SizeToFit ();
View.AddSubview (_fbShare);
_fbShare.Begin().MoveY(50).LMargin(20).Commit();
}