PropertyHandle :: HasExtension - Does property extension exist?
The function returns, whether the requested property extension exists for the instance currently selected. The function allows checking extension values as well as extension properties. When no instance is selected in the property handle, the function throws an exception.
Notes:
Property extensions just being created are accessible via this function only, when the instance or property extension has been saved (save()).
Return value: Return value ( logical )
The function returns YES when the question was answered positively. Otherwise it returns NO.