关于API帮助文档内代码的疑问求助

东边wo

问题1，我按照帮助文档的代码引用，编译器却提示如上错误（在项目引用管理器里面我就选择下面三项，没问题吧）
问题2，下面代码蓝底的“swApp”是哪来的，找不到申明
问题3，我看到网上好多都是用“swApp = CreateObject("SldWorks.Application")”引用接口的，为什么呢


Imports SOLIDWORKS.Interop.sldworks
Imports SolidWorks.Interop.swconst
Imports System.Runtime.InteropServices
Imports System
Imports System.Diagnostics


Partial Class SolidWorksMacro

    Dim swModel As ModelDoc2
    Dim selMgr As SelectionMgr
    Dim swPart As PartDoc
    Dim mirrorFeature As Feature
    Dim myFeature As Feature
    Dim resultPart As ModelDoc2
    Dim mirrorFeatData As MirrorPartFeatureData
    Dim refPlane As RefPlane
    Dim facePlane As Face2
    Dim mirrorOptions As Integer
    Dim faceType As Integer
    Dim selType As swSelectType_e
    Dim message As String

    Sub main()

        swModel = swApp.ActiveDoc

        If swModel Is Nothing Then Exit Sub
        If swModel.GetType <> swDocumentTypes_e.swDocPART Then Exit Sub

        selMgr = swModel.SelectionManager

        If selMgr.GetSelectedObjectCount2(-1) = 0 Then Exit Sub

        selType = selMgr.GetSelectedObjectType3(1, -1)
        If Not (selType = swSelectType_e.swSelDATUMPLANES Or selType = swSelectType_e.swSelFACES) Then Exit Sub

        swPart = swModel

      
    .............字数限制，省略
        End If

    End Sub


    Public swApp As SldWorks


End Class

东边wo