XamarinDevDays/Demos/app-myweather/MyWeather.iOS/AppDelegate.cs

using Foundation;
using System;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

namespace MyWeather.iOS
{
	// The UIApplicationDelegate for the application. This class is responsible for launching the
	// User Interface of the application, as well as listening (and optionally responding) to application events from iOS.
	[Register ("AppDelegate")]
	public class AppDelegate : FormsApplicationDelegate
    {
		
		public override bool FinishedLaunching (UIApplication app, NSDictionary options)
		{
            UINavigationBar.Appearance.BarTintColor = UIColor.FromRGB(43, 132, 211); //bar background
            UINavigationBar.Appearance.TintColor = UIColor.White; //Tint color of button items
            UINavigationBar.Appearance.SetTitleTextAttributes(new UITextAttributes()
            {
                Font = UIFont.FromName("HelveticaNeue-Light", 20f),
                TextColor = UIColor.White
            });

            Forms.Init();
            LoadApplication(new App());

            return base.FinishedLaunching(app, options);
        }

		public override void OnResignActivation (UIApplication application)
		{
			// Invoked when the application is about to move from active to inactive state.
			// This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) 
			// or when the user quits the application and it begins the transition to the background state.
			// Games should use this method to pause the game.
		}

		public override void DidEnterBackground (UIApplication application)
		{
			// Use this method to release shared resources, save user data, invalidate timers and store the application state.
			// If your application supports background exection this method is called instead of WillTerminate when the user quits.
		}

		public override void WillEnterForeground (UIApplication application)
		{
			// Called as part of the transiton from background to active state.
			// Here you can undo many of the changes made on entering the background.
		}

		public override void OnActivated (UIApplication application)
		{
			// Restart any tasks that were paused (or not yet started) while the application was inactive. 
			// If the application was previously in the background, optionally refresh the user interface.
		}

		public override void WillTerminate (UIApplication application)
		{
			// Called when the application is about to terminate. Save data, if needed. See also DidEnterBackground.
		}
	}
}