Change Visibility of Sketch Block Instances (C#)

This example shows how to hide and show sketch block instances in a drawing document.
//------------------------------------------------- 
// Preconditions:
// 1. Drawing document containing a sketch block
//    with one or more sketch block instances is open.
// 2. The sketch block is selected in the FeatureManager
//    design tree.
//
// Postconditions: All sketch block instances are hidden if visible, or
// shown if hidden.
//-------------------------------------------------
using SolidWorks.Interop.sldworks;
using SolidWorks.Interop.swconst;
using System;
using System.Diagnostics;
using System.Windows.Forms;

namespace VisibleSketchBlockInstanceCSharp.csproj
{
    partial class SolidWorksMacro
    {
        public void Main()
        {
            ModelDoc2 swModelDoc;
            SelectionMgr swSelMgr;
            Feature swFeature;
            SketchBlockDefinition swBlockDefinition;
            SketchBlockInstance swBlockInstance;
            object[] blocks = null;
            int i = 0;

            swModelDoc = (ModelDoc2)swApp.ActiveDoc;
            swSelMgr = (SelectionMgr)swModelDoc.SelectionManager;

            // Block feature is selected in FeatureManager design tree
            swFeature = (Feature)swSelMgr.GetSelectedObject6(1, -1);
            if (swFeature == null)
            {
                MessageBox.Show("Select a sketch block in the FeatureManager design tree, then rerun the macro.");
            }
            else
            {
                swBlockDefinition = (SketchBlockDefinition)swFeature.GetSpecificFeature2();
                Debug.Print("Feature type : " + swFeature.GetTypeName2());
                if ((swBlockDefinition != null))
                {
                    blocks = (object[])swBlockDefinition.GetInstances();
                    for (i = blocks.GetLowerBound(0); i <= blocks.GetUpperBound(0); i++)
                    {

                        swBlockInstance = (SketchBlockInstance)blocks[i];
                        Debug.Print("Sketch block instance: " + (i + 1));
                        Debug.Print(" Angle : " + swBlockInstance.Angle);
                        Debug.Print(" Scale : " + swBlockInstance.Scale2);

                        // Hide or show the sketch block instance
                        long status = 0;
                        status = swBlockInstance.Visible;
                        switch (status)
                        {
                            case (int)swAnnotationVisibilityState_e.swAnnotationHidden:
                                swBlockInstance.Visible = (int)swAnnotationVisibilityState_e.swAnnotationVisible;
                                Debug.Print(" Was hidden, now visible.");
                                break;
                            case (int)swAnnotationVisibilityState_e.swAnnotationVisible:
                                swBlockInstance.Visible = (int)swAnnotationVisibilityState_e.swAnnotationHidden;
                                Debug.Print(" Was visible, now hidden.");
                                break;
                            case (int)swAnnotationVisibilityState_e.swAnnotationHalfHidden:
                                MessageBox.Show("This block is half hidden.");
                                break;
                            case (int)swAnnotationVisibilityState_e.swAnnotationVisibilityUnknown:
                                MessageBox.Show("Failed to determine visibility of this block.");
                                break;

                        }
                    }
                }


                blocks = null;


            }
        }

        /// <summary>
        /// The SldWorks swApp variable is pre-assigned for you.
        /// </summary>
        public SldWorks swApp;


    }
}