In my case is very common to have recurrent appointments with some instances deleted.

Is there a way to only pass the instance dates where the appointment is deleted to the recurrence object?
or Do I have always to generate the items and mark them as deleted?

Thanks in advance for your help.

Unfortunately, the only way to mark an item as deleted occurrence of a recurring pattern programatically, is by generating the item and calling Recurrence.MarkException passing a reference to the item and true as parameters. I am not sure what do you mean by 'passing the instance dates to the recurrence object'. If you can explain this a bit further we might be able to expand the public interface to support it.

Meppy

Here is a simple method that can help you to achieve the desired functionality:

private void DeleteOccurrences(Item item, ArrayList toDelete)
{
    if (item.Recurrence == null)
	  return;

    // Find the interval in which to generate the items,
    // by inspecting the values passed in the second argument
    DateTime from = DateTime.MaxValue;
    DateTime to = DateTime.MinValue;

    foreach (DateTime date in toDelete)
    {
	  if (from > date)
		from = date;
	  if (to < date)
		to = date;
    }

    if (from == DateTime.MaxValue ||
	  to == DateTime.MinValue)
	  return;

    ItemCollection items = item.Recurrence.GenerateItems(from, to);

    foreach (Item occurrence in items)
    {
	  // Check if the item should be marked as deleted
	  bool delete = false;
	  foreach (DateTime date in toDelete)
	  {
		if (occurrence.StartTime <= date && date <= occurrence.EndTime)
		{
		    delete = true;
		    break;
		}
	  }

	  if (delete)
		item.Recurrence.MarkException(occurrence, true);
    }

    // Invalidate the calendar
    calendar1.Invalidate();
} 

The method accepts as first argument the master item whose occurrences should be marked as deleted and an array of DateTime objects, specifying the date and time of the occurrences of interest.

Meppy