Creating grouping for C# ArcObjects UniqueValueRenderer?

Question

Within a C# procedure I am able to successfully render discrete data values using:

pValRen.AddValue("A11", fieldName, (ISymbol)pExpressWay);
pValRen.AddValue("A15", fieldName, (ISymbol)pExpressWay);

where pValRen is a UniqueValueRenderer() object, and, the strings "A11" and "A15" refer to discrete data values. But, I need to group "A11" and "A15" together with a single reference value as suggested in the online help.

I have attempted to create a group using:

pValRen.AddReferenceValue("A15", pValRen.ReferenceValue["A11"]); 

or

pValRen.AddValue(pValRen.ReferenceValue["A11"], fieldName, (ISymbol)pExpressWay);

but, both of these approaches result in an error. How does one construct and use a ReferenceValue for the UniqueValueRenderer?

Answer 1

First you have to add a value, in your case this would be "A11" and then add the reference value(s), i.E. "A15". In my codesnippet i have an array arLiterals with all items to group:

    string sRefV=arLiterals[0];
    pValRen.AddValue(sRefV, sHeading, iSymbol);
    pValRen.set_Label(sRefV, sClassLabel);
    if (arLiterals.Length > 1)
    {
      for (int l = 1; l < arLiterals.Length; l++)
      {
          pValRen.AddReferenceValue(arLiterals[l], sRefV);
      }
    }