UI is not rendering for the same way on iOS 10.1 and iOS 10.4

Hello,

I work on a Xamarin.Forms app where I need to implement transparent/translucent navigation bar.

I've studied the the Vision Conference sample, where this is implemented.

This is achieved through a CustomNavigationPage and a CustomRenderer.

The XAML of the CustomNavigationPage is:

<?xml version="1.0" encoding="utf-8" ?>
<NavigationPage 
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    x:Class="ConferenceVision.Views.CustomNavigationPage"
    xmlns:iOS="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
    iOS:NavigationPage.IsNavigationBarTranslucent="True"
    BarTextColor="{StaticResource NavigationBarTextColor}">
    <NavigationPage.BarBackgroundColor>
        <OnPlatform x:TypeArguments="Color">
            <On Platform="Android, iOS" Value="Transparent" />
            <On Platform="UWP" Value="{StaticResource NavigationBarBackgroundColor}" />
        </OnPlatform>
    </NavigationPage.BarBackgroundColor>
</NavigationPage>

The code-behind of the CustomNavigationPage is:

public partial class CustomNavigationPage : NavigationPage
{
    public bool IgnoreLayoutChange { get; set; } = false;

    protected override void OnSizeAllocated(double width, double height)
    {
        if (!IgnoreLayoutChange)
            base.OnSizeAllocated(width, height);
    }

    public CustomNavigationPage() : base()
    {
        InitializeComponent();
    }

    public CustomNavigationPage(Page root) : base(root)
    {
        InitializeComponent();
    }
}

And the CustomRenderer is:

public class CustomNavigationRenderer : NavigationRenderer
{
    public override void ViewDidLoad()
    {
        base.ViewDidLoad();

        UINavigationBar.Appearance.SetBackgroundImage(new UIImage(), UIBarMetrics.Default);
        UINavigationBar.Appearance.ShadowImage = new UIImage();
        UINavigationBar.Appearance.BackgroundColor = UIColor.Clear;
        UINavigationBar.Appearance.TintColor = UIColor.White;
        UINavigationBar.Appearance.BarTintColor = UIColor.Clear;
        UINavigationBar.Appearance.Translucent = true;
        UINavigationBar.Appearance.SetTitleTextAttributes(new UITextAttributes()
        {
            Font = UIFont.FromName("HelveticaNeue-Light", (nfloat)20f),
            TextColor = UIColor.White
        });
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
        }

        base.Dispose(disposing);
    }
}

I've tested the app on :

• simulators : iPhone 6 on iOS 11.3
• my device : iPhone 6 on iOS 10.1

And we can see that the results are not the same. On the simulator and iOS 11.3, there is a gap between the navigation bar and the content:

But on my device under iOS 10.1, there is no gap and the content is displayed "under" the navigation bar:

The page is built like that, but the rendering is the same on all pages:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:effects="clr-namespace:ConferenceVision.Effects"
             xmlns:local="clr-namespace:ConferenceVision.Views.Renderers"
             xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"              
             ios:Page.UseSafeArea="true"
             Title="About"
             x:Class="ConferenceVision.Views.AboutView">
    <ContentPage.Content>
            <ScrollView>
                <ScrollView.Margin>
                    <OnPlatform x:TypeArguments="Thickness" Default="15,0">
                        <On Platform="Android" Value="15,50,15,0"/>
                    </OnPlatform>
                </ScrollView.Margin>
                ...
            </ScrollView>
    </ContentPage.Content>
</ContentPage>

How explain it? Could this be related to the use of UseSafeArea?
I know that I get an "old" version on my device, but in my app I have to cover the largest number of users.