void CommonInit()
{
fhvc = new MDCFlexibleHeaderViewController();
AddChildViewController(fhvc);
CGRect imageViewFrame = fhvc.HeaderView.Bounds;
imageView = new UIImageView(imageViewFrame);
imageView.ContentMode = UIViewContentMode.ScaleAspectFill;
imageView.AutoresizingMask = UIViewAutoresizing.FlexibleWidth |
UIViewAutoresizing.FlexibleHeight;
fhvc.HeaderView.AddSubview(imageView);
appBar = new MDCAppBar();
AddChildViewController(appBar.HeaderViewController);
appBar.HeaderViewController.HeaderView.BackgroundColor = UIColor.Clear;
appBar.NavigationBar.TintColor = UIColor.White;
var backButton = new UIBarButtonItem("", UIBarButtonItemStyle.Done, DidTapBack);
var backImage = UIImage.FromBundle("Back");
backButton.Image = backImage;
NavigationItem.LeftBarButtonItem = backButton;
}