Xamarin iOS Cannot access a disposed object, Object name: ''

Question

I am working with xamarin forms project and I have a bug on xamarin iOS project. Currently I implemented functionality of Master-Detail Page and also I added button item on action bar. Problem is when I am running application from my MainPage I am moving to another page from my burger menu and then back again to MainPage , everything seems good. But when I scroll my MainPage carousel to another object and I click on ActionBar item I am receiving such a error:

System.ObjectDisposedException: Cannot access a disposed object.

Object name: 'CustomNavigationRenderer'.

This is my iOS CustomNavigationRenderer class:

[assembly: ExportRenderer(typeof(NavigationPage), typeof(CustomNavigationRenderer))]
public class CustomNavigationRenderer : NavigationRenderer
{
    private string pName;
    private int pCCount;
    private string pCName;

    private App MainApp { get; set; }
    public override void ViewDidLoad()
    {
        base.ViewDidLoad();
    }
    private void CIndexChanged(int pCCount, string pName)
    {    
        UIBarButtonItem providerBtn = TopViewController.NavigationItem.RightBarButtonItems[0];
    }

On debug TopViewController I got such a line:

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'CustomNavigationRenderer'.

But until I scroll from current object to another carousel view object TopViewController have such a line on debug mode:

Xamarin_Forms_Platform_iOS_NavigationRenderer_ParentingViewController

What could be main reason, that object do not reach that action bar item?

score 1 · Accepted Answer · answered Aug 26 '16 at 14:31

I solved this issue by do not creating new Navigation page all the time , but reusing existing Navigation page. Here is my Navigation items method where I am taking items from existing list. I reused Main page:

private void ListView_ItemSelect(object sender, SelectedItemChangedEventArgs e)
        {
            var selectedItem = (MasterMenuItem)((ListView)sender).SelectedItem;

            MainPage mainPage = (App.Current.MainPage as MainPage);
            switch (selectedItem.KeyIndexName)
            {
                case "MainPage":
                    mainPage.Detail = mainPage.MainPageDetail;
                    break;
                case "AAA":
                    if(aaa==null)
                        aaa = new NavigationPage(new AaaPage());
                    mainPage.Detail = aaa;
                    break;
                case "BBB":
                    if (bbb== null)
                        bbb = new NavigationPage(new BbbPage());
                    mainPage.Detail = bbb;
                    break;
                case "CCC":
                    if (ccc == null)
                        ccc = new NavigationPage(new CccPage());
                    mainPage.Detail = ccc;
                    break;
            };
            mainPage.IsPresented = false;
        }

Xamarin iOS Cannot access a disposed object, Object name: ''

1 Answers1