DocumentNew | 
public FamilyInstance NewFamilyInstance( Curve curve, FamilySymbol symbol, Level level, StructuralType structuralType )
| Exception | Condition | 
|---|---|
| ArgumentException | Thrown if the family symbol does not exist in the given document. | 
| ArgumentException | Thrown if the level does not exist in the given document. | 
| ArgumentException | Thrown if The symbol is not active. | 
The type/symbol that is used must be loaded into the document before this method is called. Families and their symbols can be loaded using the Document.LoadFamily or Document.LoadFamilySymbol methods.
The host object must be one that supports insertion of instances otherwise this method will fail. All levels within the document can be found by iterating over the entire document and searching for objects of type Autodesk.Revit.Elements.Level.
Note: if the created family instance includes nested instances, the API framework will automatically regenerate the document during this method call.
FamilyInstance CreateBeam(Autodesk.Revit.DB.Document document, View view)
{
   // get the given view's level for beam creation
    Level level = document.GetElement(view.LevelId) as Level;
    // get a family symbol
    FilteredElementCollector collector = new FilteredElementCollector(document);
    collector.OfClass(typeof(FamilySymbol)).OfCategory(BuiltInCategory.OST_StructuralFraming);
    FamilySymbol gotSymbol = collector.FirstElement() as FamilySymbol;
    // create new beam 10' long starting at origin
    XYZ startPoint = new XYZ(0, 0, 0);
    XYZ endPoint = new Autodesk.Revit.DB.XYZ(10, 0, 0);
    Autodesk.Revit.DB.Curve beamLine = Line.CreateBound(startPoint, endPoint);
    // create a new beam
    FamilyInstance instance = document.Create.NewFamilyInstance(beamLine, gotSymbol,
                                                                level, StructuralType.Beam);
    return instance;
}