Custom renderer for Xamarin.Forms TimePicker on iOS. This will make the TimePicker always show time using 24H format (aka no AM or PM).

TimePicker24HRenderer.cs

using MonoTouch.Foundation;
using MonoTouch.UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
using PersonalTrainer.iOS.View.Controls;

[assembly: ExportRenderer (typeof (TimePicker), typeof (TimePicker24HRenderer))]

namespace YourNamespace.iOS.View.Controls {
	public class TimePicker24HRenderer : TimePickerRenderer {
		protected override void OnElementChanged(ElementChangedEventArgs<TimePicker> e) {
			base.OnElementChanged(e);
			var timePicker = (UIDatePicker)Control.InputView;
			timePicker.Locale = new NSLocale("no_nb");
		}
	}
}