I have just developed a method that allows me to create a floor. Being new to the Revit API, it seems to me that the floor I just created exists but is not yet visible on Revit.

How do I make this floor visible in Revit?

I might be wrong, in which case I would be happy if you could explain the problem to me.

public Result CreateFloor(UIApplication uiapp)
{
    UIDocument uiDoc = uiapp.ActiveUIDocument;
    Autodesk.Revit.ApplicationServices.Application app = uiapp.Application;
    Document doc = uiDoc.Document;

    using (Transaction transaction = new Transaction(doc))
    {

        if (transaction.Start("Create floor") == TransactionStatus.Started)
        {
            XYZ[] points = new XYZ[3];
            points[0] = new XYZ(0,0,0);
            points[1] = new XYZ(0,10,0);
            points[2] = new XYZ(10,0,0);

            CurveArray curve = new CurveArray();

            Line line1 = Line.CreateBound(points[0], points[1]);
            Line line2 = Line.CreateBound(points[1],points[2]);
            Line line3 = Line.CreateBound(points[2], points[0]);
            curve.Append(line1);
            curve.Append(line2);
            curve.Append(line3);

            Floor floor=doc.Create.NewFloor(curve, false);
            return Result.Succeeded;
        }
        else
        {
            transaction.RollBack();
            return Result.Failed;
        }
    }
}