[Epicalsoft: Xamarin] Fuentes personalizadas en aplicaciones Xamarin.Forms

AppLabel.cs

using Xamarin.Forms;

namespace _20160228.Controls
{
    public class AppLabel : Label
    {
        public static readonly BindableProperty FontNameProperty =
            BindableProperty.Create<AppLabel, string>(
                p => p.FontName, null, BindingMode.TwoWay);

        public string FontName
        {
            get
            {
                return (string)GetValue(FontNameProperty);
            }

            set
            {
                SetValue(FontNameProperty, value);
            }
        }
    }
}

AppLabelRenderer_Android.cs

using _20160228.Controls;
using _20160228.Droid.Renderers;
using Android.Graphics;
using System;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(AppLabel), typeof(AppLabelRenderer))]

namespace _20160228.Droid.Renderers
{
    public class AppLabelRenderer : LabelRenderer
    {
        public AppLabelRenderer()
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<Label> e)
        {
            base.OnElementChanged(e);

            if (null != Control)
            {
                var fontName = ((AppLabel)e.NewElement).FontName;
                Control.Typeface = TryGetFont(fontName);
            }
        }

        private Typeface TryGetFont(string fontName)
        {
            try
            {
                if (fontName == "MagistralC")
                    return Typeface.CreateFromAsset(Forms.Context.Assets, "MagistralC.otf");
                if (fontName == "Radical Beat")
                    return Typeface.CreateFromAsset(Forms.Context.Assets, "RadicalBeat.ttf");
                else
                    return Typeface.Default;
            }
            catch (Exception)
            {
                return Typeface.Default;
            }
        }
    }
}

AppLabelRenderer_iOS.cs

using _20160228.Controls;
using _20160228.iOS.Renderers;
using System;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(AppLabel), typeof(AppLabelRenderer))]

namespace _20160228.iOS.Renderers
{
    public class AppLabelRenderer : LabelRenderer
    {
        public AppLabelRenderer()
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<Label> e)
        {
            base.OnElementChanged(e);

            if (null != Control)
            {
                var fontName = ((AppLabel)e.NewElement).FontName;
                Control.Font = TryGetFont(fontName, (float)e.NewElement.FontSize);
            }
        }

        private UIFont TryGetFont(string fontName, float fontSize)
        {
            try
            {
                return UIFont.FromName(fontName, fontSize);
            }
            catch (Exception)
            {
                var defaultFontName = UIFont.FontNamesForFamilyName(UIFont.FamilyNames[0])[0];
                return UIFont.FromName(defaultFontName, fontSize);
            }
        }
    }
}

Info.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <!-- Código omitido por legibilidad -->
  <key>UIAppFonts</key>
  <array>
    <string>Fonts/MagistralC.otf</string>
    <string>Fonts/RadicalBeat.ttf</string>
  </array>
</dict>
</plist>

MainPage.xaml

<?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:controls="clr-namespace:_20160228.Controls"
             x:Class="_20160228.Views.MainPage">
  <StackLayout VerticalOptions="Center" HorizontalOptions="Center">
    <Label Text="Magistral" FontSize="Large"/>
    <controls:AppLabel Text="Reach" FontSize="Small" FontName="MagistralC"/>
    <controls:AppLabel Text="Reach" FontSize="Medium" FontName="MagistralC"/>
    <controls:AppLabel Text="Reach" FontSize="Large" FontName="MagistralC"/>
    <Label Text="Radical Beat" FontSize="Large"/>
    <controls:AppLabel Text="Reach" FontSize="Small" FontName="Radical Beat"/>
    <controls:AppLabel Text="Reach" FontSize="Medium" FontName="Radical Beat"/>
    <controls:AppLabel Text="Reach" FontSize="Large" FontName="Radical Beat"/>
  </StackLayout>
</ContentPage>