Xamarin Slide up from bottom modal view transition for iOS 7

gistfile1.cs

	public class TransitioningDelegate : UIViewControllerTransitioningDelegate
	{

		public override IUIViewControllerAnimatedTransitioning PresentingController (UIViewController presented, UIViewController presenting, UIViewController source)
		{
			return new ModalSlideUpAnimator ();
		}

		public override IUIViewControllerAnimatedTransitioning GetAnimationControllerForDismissedController (UIViewController dismissed)
		{
			return new ModalSlideUpAnimator (true); 
		}

	}

	public class ModalSlideUpAnimator : UIViewControllerAnimatedTransitioning
	{
		bool reverse = false; 
		float length = 0.5f; 

		public ModalSlideUpAnimator ()
		{
		}
		public ModalSlideUpAnimator (float length)
		{
			this.length = length; 
		}
		public ModalSlideUpAnimator(bool reverse) {
			this.reverse = reverse; 
		}
		public ModalSlideUpAnimator(float length, bool reverse) {
			this.reverse = reverse; 
			this.length = length; 
		}

		public override double TransitionDuration (IUIViewControllerContextTransitioning transitionContext)
		{
			return length;
		}

		public override void AnimateTransition (IUIViewControllerContextTransitioning transitionContext)
		{
			var inView = transitionContext.ContainerView;
			var fromVC = transitionContext.GetViewControllerForKey (UITransitionContext.FromViewControllerKey);
			var fromView = fromVC.View;
			var toVC = transitionContext.GetViewControllerForKey (UITransitionContext.ToViewControllerKey);
			var toView = toVC.View;



			var frame = toView.Frame;

			if (reverse) {
				inView.InsertSubviewBelow (toView, fromVC.View); 
			} else {
				inView.AddSubview (toView);
				toView.Frame = new System.Drawing.RectangleF (0, inView.Frame.Height, frame.Width, frame.Height);

			}
			UIView.Animate (TransitionDuration (transitionContext), () => {
				if (reverse) {
					fromView.Frame = new System.Drawing.RectangleF (0, inView.Frame.Height, frame.Width, frame.Height);

				} else {
					toView.Frame = new System.Drawing.RectangleF (0, UIApplication.SharedApplication.StatusBarFrame.Size.Height, frame.Width, frame.Height);
				}
			}, () => {
				transitionContext.CompleteTransition (true);
			});
		}



	}