public static SldWorks swApp = (SldWorks)Marshal.GetActiveObject("SldWorks.Application");

如果是有多个版本的SW，可能需要区分：
(SldWorks)Marshal.GetActiveObject("SldWorks.Application.26");//2018
(SldWorks)Marshal.GetActiveObject("SldWorks.Application.27");//2019
(SldWorks)Marshal.GetActiveObject("SldWorks.Application.28");//2020……

swApp.OpenDoc(filename, (int)swDocumentTypes_e.swDocPART); //Fun（文件路径，文件类型）：

PartDoc swPart = (AssemblyDoc)swApp.ActiveDoc;//类型1：零件
AssemblyDoc swAssy = (AssemblyDoc)swApp.ActiveDoc; //类型2：装配体
DrawingDoc swDraw = (AssemblyDoc)swApp.ActiveDoc; //类型3：工程图

//获得自定义属性对象（配置属性在双引号填“配置名称”）
CustomPropertyManager cusPropMgr = swDoc.Extension.CustomPropertyManager[""];

Get：
//GetAll获得自定义属性内容，将obj转属性名数组
cusPropMgr.GetAll2(ref vPropNamesObject, ref vPropTypes, ref vPropValues, swCustomInfoGetResult_e.swCustomInfoGetResult_NotPresent);
object[] vPropNames = (object[])vPropNamesObject; if (vPropNames == null) { return; }

Set：
增：Add(属性名,类型,属性值,添加时的设置)
cusPropMgr.Add3(PropertyName, (int)swCustomInfoType_e.swCustomInfoText, PropertyValue, (int)swCustomPropertyAddOption_e.swCustomPropertyDeleteAndAdd);//输入属性内容
改：
vPropNames[i]=””
删：
cusPropMgr.Delete2((string)vPropNames[i]);

/// <summary>
/// 遍历特征对象
/// </summary>
public static void TraverseFeatures(bool isTopLevel)
        {
            //获得第一个特征，并赋值到当前特征curFeat
            Feature thisFeat = (Feature)swDoc.FirstFeature();
            Feature curFeat = default(Feature); curFeat = thisFeat;

            //当前特征非空就继续输出特征信息
            while ((curFeat != null))
            {
                Debug.Print(curFeat.Name);
                //特征操作
                bool isShowDimension = false; if (isShowDimension == true) ShowDimensionForFeature(curFeat);
    
                /*//子特征的遍历
                Feature subfeat = default(Feature);
                subfeat = (Feature)curFeat.GetFirstSubFeature();
                while ((subfeat != null))
                {
                    //if (isShowDimension == true) ShowDimensionForFeature(subfeat);
                    TraverseFeatures(subfeat, false);
                    Feature nextSubFeat = default(Feature);
                    nextSubFeat = (Feature)subfeat.GetNextSubFeature();
                    subfeat = nextSubFeat; nextSubFeat = null;
                }
                subfeat = null;*/
    
                //进入下一个特征
                Feature nextFeat = default(Feature);
                if (isTopLevel) { nextFeat = (Feature)curFeat.GetNextFeature(); }
                else { nextFeat = null; }
    
                curFeat = nextFeat; nextFeat = null;
            }
        }

public static string[] GetComps()
        {
            //打开文件&获得零部件集合
            AssemblyDoc swAssy = (AssemblyDoc)swApp.ActiveDoc; 
            string[] Comppaths = (string[])swAssy.GetComponents(true); return Comppaths;
        }

public static void GetSheetNames()
        {
            Sheet drwSheet = (Sheet)swDraw.GetCurrentSheet();       //获取当前工程图对象
            object[] sheetNames = (object[])swDraw.GetSheetNames(); //获取当前工程图中的所有图纸名称
            object[] views = (object[])drwSheet.GetViews();         //获取当前工程图中的所有图纸视图

            foreach (View view in views)//遍历工程图零部件,输入选择视图,输出零部件名
            {
                DrawingComponent comp = view.RootDrawingComponent; Debug.Print(comp.Name); //选择视图激活
                object[] childrencomps = (object[])comp.GetChildren();//获得子件对象
                //遍历工程图零部件
                for (int i = childrencomps.GetLowerBound(0); i <= childrencomps.GetUpperBound(0); i++)
                {
                    Debug.Print("零部件是" + ((DrawingComponent)childrencomps[i]).Name);
                }
            }
        }