NFrame.NFCDataList.StringVal C# (CSharp) Method

        public override string StringVal(int index)
        {
            TData data = GetData(index);
            if (data != null && data.GetType() == VARIANT_TYPE.VTYPE_STRING)
            {
                return data.StringVal();
            }

            return NFIDataList.NULL_STRING;
        }

        public override void Update(float fPassTime)
        {
            NFIDataList xRemoveKeyList = new NFCDataList();;

            foreach (KeyValuePair <string, NFIHeartBeat> kv in mhtHeartBeat)
            {
                NFIHeartBeat xHeartBeat = (NFIHeartBeat)kv.Value;
                if (xHeartBeat.NeedRemove())
                {
                    xRemoveKeyList.AddString((string)kv.Key);
                }
                else
                {
                    xHeartBeat.Update(fPassTime);
                }
            }

            for (int i = 0; i < xRemoveKeyList.Count(); i++)
            {
                mhtHeartBeat.Remove(xRemoveKeyList.StringVal(i));
            }
        }