void UpdateStyle()
{
var navigationBarAppearance = NavigationBar.StandardAppearance;
var titleTextAttributes = new UIStringAttributes
{
Font = UIFont.FromName((string)Xamarin.Forms.Application.Current.Resources["font_semibold"], 16)
};
var title = new UIStringAttributes
{
ForegroundColor = Xamarin.Forms.Application.Current.RequestedTheme == OSAppTheme.Light ?
((Color)Xamarin.Forms.Application.Current.Resources["black"]).ToUIColor() :
((Color)Xamarin.Forms.Application.Current.Resources["white"]).ToUIColor(),
Font = UIFont.FromName((string)Xamarin.Forms.Application.Current.Resources["font_bold"], 18)
};
var titleText = new UITextAttributes
{
TextColor = title.ForegroundColor,
Font = title.Font
};
navigationBarAppearance.TitleTextAttributes = title;
if (titleTextAttributes.Dictionary.Keys.Any())
{
var dic = new NSDictionary <NSString, NSObject>(
new NSString[] { titleTextAttributes.Dictionary.Keys[0] as NSString }, titleTextAttributes.Dictionary.Values
);
var button = new UIBarButtonItemAppearance(UIBarButtonItemStyle.Plain);
button.Normal.TitleTextAttributes = dic;
button.Highlighted.TitleTextAttributes = dic;
navigationBarAppearance.ButtonAppearance = button;
}
NavigationBar.StandardAppearance = navigationBarAppearance;
NavigationBar.CompactAppearance = navigationBarAppearance;
NavigationBar.ScrollEdgeAppearance = navigationBarAppearance;
UINavigationBar.Appearance.SetTitleTextAttributes(titleText);
}
protected override void Render()
{
ApplyVisibility();
var appearance = new UINavigationBarAppearance();
// Background
var backgroundColor = Brush.GetColorWithOpacity(Element.Background);
switch (backgroundColor)
{
case { } opaqueColor when opaqueColor.A == byte.MaxValue:
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
appearance.ConfigureWithOpaqueBackground();
appearance.BackgroundColor = opaqueColor;
}
else
{
// Prefer BarTintColor because it supports smooth transitions
Native.BarTintColor = opaqueColor;
Native.Translucent = false; //Make fully opaque for consistency with SetBackgroundImage
Native.SetBackgroundImage(null, UIBarMetrics.Default);
Native.ShadowImage = null;
}
break;
case { } semiTransparentColor when semiTransparentColor.A > 0:
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
appearance.ConfigureWithDefaultBackground();
appearance.BackgroundColor = semiTransparentColor;
}
else
{
Native.BarTintColor = null;
// Use SetBackgroundImage as hack to support semi-transparent background
Native.SetBackgroundImage(((UIColor)semiTransparentColor).ToUIImage(), UIBarMetrics.Default);
Native.Translucent = true;
Native.ShadowImage = null;
}
break;
case { } transparent when transparent.A == 0:
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
appearance.ConfigureWithTransparentBackground();
appearance.BackgroundColor = transparent;
}
else
{
Native.BarTintColor = null;
Native.SetBackgroundImage(new UIImage(), UIBarMetrics.Default);
// We make sure a transparent bar doesn't cast a shadow.
Native.ShadowImage = new UIImage(); // Removes the default 1px line
Native.Translucent = true;
}
break;
default: //Background is null
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
appearance.ConfigureWithDefaultBackground();
appearance.BackgroundColor = null;
}
else
{
Native.BarTintColor = null;
Native.SetBackgroundImage(null, UIBarMetrics.Default); // Restores the default blurry background
Native.ShadowImage = null; // Restores the default 1px line
Native.Translucent = true;
}
break;
}
// Foreground
if (Brush.TryGetColorWithOpacity(Element.Foreground, out var foregroundColor))
{
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
appearance.TitleTextAttributes = new UIStringAttributes
{
ForegroundColor = foregroundColor,
};
appearance.LargeTitleTextAttributes = new UIStringAttributes
{
ForegroundColor = foregroundColor,
};
}
else
{
Native.TitleTextAttributes = new UIStringAttributes
{
ForegroundColor = foregroundColor,
};
}
}
else
{
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
appearance.TitleTextAttributes = new UIStringAttributes();
appearance.LargeTitleTextAttributes = new UIStringAttributes();
}
else
{
Native.TitleTextAttributes = null;
}
}
// CommandBarExtensions.BackButtonForeground
var backButtonForeground = Brush.GetColorWithOpacity(Element.GetValue(BackButtonForegroundProperty) as Brush);
Native.TintColor = backButtonForeground;
// CommandBarExtensions.BackButtonIcon
var backButtonIcon = Element.GetValue(BackButtonIconProperty) is BitmapIcon bitmapIcon
? UIImageHelper.FromUri(bitmapIcon.UriSource)?.ImageWithRenderingMode(UIImageRenderingMode.AlwaysOriginal)
: null;
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
var backButtonAppearance = new UIBarButtonItemAppearance(UIBarButtonItemStyle.Plain);
if (backButtonForeground is { } foreground)
{
var titleTextAttributes = new UIStringAttributes
{
ForegroundColor = foreground
};
var attributes = new NSDictionary <NSString, NSObject>(
new NSString[] { titleTextAttributes.Dictionary.Keys[0] as NSString }, titleTextAttributes.Dictionary.Values
);
backButtonAppearance.Normal.TitleTextAttributes = attributes;
backButtonAppearance.Highlighted.TitleTextAttributes = attributes;
if (backButtonIcon is { } image)
{
var tintedImage = image.ApplyTintColor(foreground);
appearance.SetBackIndicatorImage(tintedImage, tintedImage);
}
}
else
{
if (backButtonIcon is { } image)
{
appearance.SetBackIndicatorImage(image, image);
}
}
appearance.BackButtonAppearance = backButtonAppearance;
}
