UIHelpers.cs

public class UIHelpers 
{ 
    MyPage view; 
    public UIHelpers() 
    { 
        if(!Forms.IsInitialized) 
            Forms.Init(); 
        view = new MyPage(); 
    } 


    public void ShowMyPage() 
    { 
        var controller = view.CreateViewController(); 
        var vc = GetVisibleViewController(); 

        if (vc.NavigationController != null) 
            vc.NavigationController.PushViewController(controller, true); 
        else 
            vc.PresentViewController(controller, true, () => { }); 
    } 

    UIViewController GetVisibleViewController() 
    { 
        UIViewController viewController = null; 
        var window = UIApplication.SharedApplication.KeyWindow; 


        if (window != null && window.WindowLevel == UIWindowLevel.Normal) 
            viewController = window.RootViewController; 

        if (viewController == null) 
        { 
            window = UIApplication.SharedApplication.Windows.OrderByDescending(w => w.WindowLevel).FirstOrDefault(w => w.RootViewController != null && w.WindowLevel == UIWindowLevel.Normal); 
            if (window == null) 
                throw new InvalidOperationException("Could not find current view controller"); 
            else 
                viewController = window.RootViewController; 
        } 

        while (viewController.PresentedViewController != null) 
            viewController = viewController.PresentedViewController; 

        var navController = viewController as UINavigationController; 
        if (navController != null) 
            viewController = navController.ViewControllers.Last(); 

        return viewController; 
    } 
}