Implementing INotifyCollectionChanged on custom list

Question

I currently have a class in UWP that is a wrapper for a bunch of different types of lists, including a custom-list that I have built. This wrapper needs to bind to some sort of list, either ListView, ListBox, GridView, etc.

The problem is when I am trying to implement INotifyCollectionChanged , it seems that the UI element doesn't attatch a handler to the CollectionChanged or the PropertyChanged handlers (handlers are always null ). However, changing the list from my custom list to an ObservableCollection seems to work fine. What am I missing to get the UI to bind its collection changed to my class?

My current implementation looks like

public class MyWrapperList<T> : IList<T>, INotifyPropertyChanged, INotifyCollectionChanged
{
    private IEnumerable<T> _source;

    // Implement all interfaces here, including my custom GetEnumerator() and all my add, insert, remove, etc classes
}

Note that I would not like to inheret from ObservableCollection like many other answers suggest, due to the fact that I'd like this is a wrapper looking at the original list.

EDIT: You can find a sample of the issue reproduceable on GitHub: https://github.com/nolanblew/SampleCollectionChanged/

Answer 1

In order to have the ListView auto-bind to your collection, you must implement both INotifyCollectionChange and IList (note: that's the non-generic IList).

If you modify your sample code so that your custom list class implements IList :

public class MyWrapperList<T> : IList<T>, INotifyPropertyChanged, INotifyCollectionChanged, IList
{

    //... all your existing code plus: (add your own implementation)

    #region IList 

    void ICollection.CopyTo(Array array, int index) => throw new NotImplementedException();        
    bool IList.IsFixedSize => throw new NotImplementedException();
    bool IList.Contains(object value) => throw new NotImplementedException();       
    int IList.IndexOf(object value) => throw new NotImplementedException();
    void IList.Insert(int index, object value) => throw new NotImplementedException();
    void IList.Remove(object value) => throw new NotImplementedException();
    int IList.Add(object value) => throw new NotImplementedException();
    public bool IsSynchronized => throw new NotImplementedException();
    public object SyncRoot { get; } = new object();

    object IList.this[int index] {
        get => this[index];
        set => this[index] = (T) value;
    }
    #endregion
}

Then the CollectionChanged is set when the button click event is fired.