Custom UINavigationBar in MonoTouch

Question

I'm currently trying to create a custom navigation-bar for my navigation-controller in iOS using MonoTouch. The application I'm developing has the need to have a single string available on-screen no matter where you are on the application, and I wan't to achieve something like this (I know this is a little out off proportion, but you should be able to get the point):

+-----------------------------------------+
|  /---------|                     +---+  |
| /   Back   |     Controller Name |btn|  |
|  \---------|                     +---+  |
+-----------------------------------------+
|     Current building <- global string   |
+-----------------------------------------+

The bottom bar should be as small as possible (while not being hard to read), and the original navigation-bar might need to be a tiny bit smaller than normal.

Also, I've tried not to use the designer, but to write all the UI-code myself, but if that is impossible to achieve this, then I'll off cause have to use the designer. Currently I've found a project for creating a custom UINavigationBar in MonoTouch, but I have no idea of how to apply that to my NavigationController (see as the NavigationBar-property is read-only). The project I was talking about can be found here: https://github.com/mafis/Monotouch-Custom-Control/tree/master/CustomControls. Also, I would like the design of the actual navigationbar (the top part) to be standard iOS design, and work as a navigationbar normally would.

Any hints, or pointers at how to do this would be appreciated.

Answer 1

This is how I ended up solving this problem. I subclassed UIViewController like this:

using System;
using MonoTouch.UIKit;
using MonoTouch.CoreGraphics;
using System.Drawing;
using System.Collections.Generic;
using FdvWeb.Core;
namespace FdvWeb
{
    [MonoTouch.Foundation.Preserve(AllMembers=true)]
    public class MainNavigationController : UINavigationController
    {
        private const float NAV_BAR_HEIGHT = 44;
        private readonly float buildingBarTop = 44;
        private readonly float buildingBarHeight = 17;
        private readonly float viewOffset;

        private readonly HashSet<UIViewController> modifiedViewControllers = new HashSet<UIViewController>();

        UITextView buildingTextView;

        [MonoTouch.Foundation.Preserve]
        public MainNavigationController ()
        {
            viewOffset = buildingBarTop + buildingBarHeight - NAV_BAR_HEIGHT;

            var tt = new UITextView (new RectangleF (0, buildingBarTop, 320, buildingBarHeight));

            NavigationBarHidden = false;
            NavigationBar.AddSubview (tt);
            tt.Font = UIFont.BoldSystemFontOfSize (12);
            tt.TextAlignment = UITextAlignment.Center;
            tt.TextColor = UIColor.LightTextColor;
            tt.BackgroundColor = UIColor.ViewFlipsideBackgroundColor;
            tt.Editable = false;
            tt.ContentInset = new UIEdgeInsets (-9, 0, 0, 0);
            buildingTextView = tt;
        }

        public override void ViewDidLoad ()
        {
            base.ViewDidLoad ();


        }

        public override void ViewWillAppear (bool animated)
        {
            base.ViewWillAppear (animated);
        }

        public string BuildingText
        {
            get {
                return buildingTextView.Text;
            }
            set {
                container.Resolve<IUIThreadDispatcher> ().DispatchOnUIThread (delegate { // Run on UI thread
                    buildingTextView.Text = value;
                });
            }
        }

        public override void PushViewController (UIViewController viewController, bool animated)
        {
            if (!modifiedViewControllers.Contains (viewController))
            {
                viewController.View = new PaddedView (viewController.View, new InnsetF (0, viewOffset, 0, 0));
                modifiedViewControllers.Add (viewController);
            }

            viewController.NavigationItem.RightBarButtonItem = pickBuildingItem;
            base.PushViewController (viewController, animated);
        }

        private class PaddedView : UIView
        {
            private UIView view;
            private InnsetF innsets;

            public PaddedView (UIView view, InnsetF innsets)
                : base(view.Frame)
            {
                this.view = view;
                this.innsets = innsets;
                this.AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight;
                this.AddSubview (view);
            }

            public override void LayoutSubviews ()
            {
                //apply the insets to the subview
                view.Frame = new RectangleF (innsets.Left, innsets.Top,
                    Frame.Size.Width - innsets.Left - innsets.Right,
                    Frame.Size.Height - innsets.Top - innsets.Bottom);
            }
        }

        private class InnsetF
        {
            private float top, bottom, left, right;
            public InnsetF (float left, float top, float right, float bottom)
            {
                this.top = top;
                this.left = left;
                this.bottom = bottom;
                this.right = right;
            }

            public float Top
            {
                get { return top; }
                set { top = value; }
            }

            public float Bottom
            {
                get { return bottom; }
                set { bottom = value; }
            }

            public float Right
            {
                get { return right; }
                set { right = value; }
            }

            public float Left
            {
                get { return left; }
                set { left = value; }
            }
        }
    }
}

Answer 2

So you want the reverse of what Spotify does when it is offline (the string message you're referring to appears above the UINavigationController).

I don't think the approach you're taking is going to work - as far as I know, the NavigationBar can only be 44 pixels high. Could you take a similar approach to Spotify and move it above the NavigationBar? This way you could leave the NavigationController etc as is and simply make it's view smaller, then add the string to the window object - that way it will persist as you navigate through your application.