Nsryjdtyk

I order to apply some navigationBar properties (like as the background image) for different page, I think to have a condition on my custom NavigationRenderer.

My idea is to have some condition like (in my working code)

   public class CustomNavigationRenderer : NavigationRenderer

{

    public override void ViewDidLoad()

    {

        base.ViewDidLoad();



        if (pagePushed is 1)

        {

            NavigationBar.SetBackgroundImage(new UIImage(), UIBarMetrics.Default);

            NavigationBar.ShadowImage = new UIImage();

        }



        else (ahother page){

            var img = UIImage.FromBundle("MyImage");

            NavigationBar.SetBackgroundImage(img, UIBarMetrics.Default);

        }

    }

}

that allows me to have at least a condition to apply a different navigation properties. Another way is to have 2 Navigationrenderer class but I think is not possible.

Any idea to how do that?

If you look at the source code for NavigationRenderer here, you will notice there are quite a few methods and callbacks you can take advantage of.

I would suggest you can do something like this:

1) Code for your custom NavigationRenderer (iOS project, you will have to do something similar on Android):

using System.Threading.Tasks;

using MyProject.iOS;

using UIKit;

using Xamarin.Forms;

using Xamarin.Forms.Platform.iOS;



[assembly: ExportRenderer(typeof(NavigationPage), typeof(NavRenderer))]

namespace MyProject.iOS

{

    public class NavRenderer : NavigationRenderer

    {

        protected override async Task<bool> OnPushAsync(Page page, bool animated)

        {

            var result = await base.OnPushAsync(page, animated);



            if(result)

            {

                if (page is IMyPageType1)

                {

                    NavigationBar.SetBackgroundImage(new UIImage(), UIBarMetrics.Default);

                    NavigationBar.ShadowImage = new UIImage();

                }



                else if(page is IMyPageType2)

                {

                    var img = UIImage.FromBundle("MyImage");

                    NavigationBar.SetBackgroundImage(img, UIBarMetrics.Default);

                }

            }



            return result;

        }

    }

}

2) Based on the code above, you need to add two interfaces. These should be located in the same project / dll where your Pages are located (all your Xamarin.Forms UI):

    public interface IMyPageType1

    {

    }



    public interface IMyPageType2

    {

    }

3) Now everything that's remaining is implement the interfaces on the pages where you need it. For example:

    public partial class MyPage1 : ContentPage, IMyPageType1

    {

        //...

    }

From here, possibilities are endless! You can add for example a method to IMyPageType1 that would return a color, and then inside your renderer, once you know the page being pushed is implementing IMyPageType1, you can call the method and get the color to use.