Add an item at a specific index in a group

The SfListView allows adding an item at the specific index in a group by finding the group with the help of Key value of the group.

internal void GetGroupResult(object ItemData)
{
    var descriptor = listView.DataSource.GroupDescriptors[0];
    object key;
  
    if (descriptor.KeySelector == null)
    {
      var propertyInfoCollection = new PropertyInfoCollection(ItemData.GetType());
      key = propertyInfoCollection.GetValue(ItemData, descriptor.PropertyName);
    }
    else
      key = descriptor.KeySelector(ItemData);
    for (int i = 0; i < this.listView.DataSource.Groups.Count; i++)
    {
      var group = this.listView.DataSource.Groups[i];
      if ((group.Key != null && group.Key.Equals(key)) || group.Key == key)
         {
           itemGroup = group;
           break;
         }
       group = null;
     }
     itemGroup = this.listView.DataSource.Groups.FirstOrDefault(x => x.Key == key);         
     descriptor = null;
     key = null;
}

To add item at specific index in a group, follow the code example

using Syncfusion.ListView.XForms.Control.Helpers;
private void AddItem_Clicked(object sender, EventArgs e)
{
  var contact = new Contacts();
  contact.ContactName = "Adam";
  contact.ContactNumber = "783-457-567";
  contact.DisplayString = "A";
  contact.ContactImage = ImageSource.FromResource("Grouping.Images.Image" + 25 + ".png");
  ViewModel.ContactItems.Add(contact);

  GetGroupResult(contact);

  if (itemGroup == null)
      return;

   var items = itemGroup.GetType().GetRuntimeProperties().FirstOrDefault(x => x.Name == "ItemList").GetValue(itemGroup) as List<object>;
   InsertItemInGroup(items, contact, 0);
}

internal void InsertItemInGroup(List<object> items, object Item, int InsertAt)  
{
   visualContainer = listView.GetVisualContainer();
   items.Remove(Item);
   items.Insert(InsertAt, Item);
   visualContainer.ForceLayout();
}

To know more about grouping, please refer our documentation here