public bool StartEditing()

{
  // Create a new TIN 
  tinEditor = new TinEditor(MapView.Active.Extent); // or use any envelope 
  tinEditor.AddMassPoints(points, 42, 13.7);

  // Since the TIN doesn't exist on disk, you can't call SaveEdits.
  // You must call SaveAs first.
  try
  {
    tinEditor.SaveEdits();
  }
  catch (TinException)
  {
    // Handle the exception
  }

  // Since the TIN doesn't exist on disk, you can't call StopEditing(true).
  // You must call SaveAs first.
  try
  {
    tinEditor.StopEditing(true);
  }
  catch (TinException)
  {
    // Handle the exception
  }

  // Now save the newly created TIN to disk
  tinEditor.SaveAs("C:\\Tin1", false);

  // Delete a node
  tinEditor.DeleteNode(7);

  // Since the TIN now exists on disk you can call SaveEdits
  tinEditor.SaveEdits();

  // Delete another node
  tinEditor.DeleteNode(11);

  // Since the TIN now exists on disk, you can call StopEditing(true).
  // The edits will be saved and the tin editor will be taken out of edit mode.
  tinEditor.StopEditing(true);
  bool isInEditMode = tinEditor.IsInEditMode; // isInEditMode = false

  // Now if you try to make an edit, an exception is thrown because the editor is not in edit mode.
  try
  {
    tinEditor.AddPointZ(pointZ, 0);
  }
  catch (TinException)
  {
    // Handle the exception
  }

  // Put the editor into edit mode.
  tinEditor.StartEditing();
  isInEditMode = tinEditor.IsInEditMode; // isInEditMode = true

  // Now you can add the point
  tinEditor.AddPointZ(pointZ, 0);

  // Oops, you didn't really want to add the point. You want to stop editing and discard the unsaved edits
  // since the last time the editor was put into edit mode. All previous saved edits remain.
  tinEditor.StopEditing(false);
}

{
  string tinPath = "C:\\Tin"; //original TIN path
  // Create an instance of TinEditor from an existing TinDataset
  tinEditor = new TinEditor(tinDataset);
  int numNodes = tinDataset.GetNodeCount();  // numNodes = 10
  tinEditor.AddPointZ(pointZ, 7);

  // Calling SaveEdits modifies the existing TIN
  tinEditor.SaveEdits();
  numNodes = tinDataset.GetNodeCount();  // numNodes = 11

  // Adding twenty points
  tinEditor.AddMassPoints(points, 10, 112.5);

  // Calling SaveAs creates a new TIN on disk, and 
  // the tin editor points to the new TIN.
  string tinPath2 = "C:\\Tin2";
  tinEditor.SaveAs(tinPath2, true);

  tinEditor.StopEditing(true);
  var connection = new FileSystemConnectionPath(new Uri(Path.GetDirectoryName(tinPath2)), FileSystemDatastoreType.Tin);
  using (FileSystemDatastore dataStore = new FileSystemDatastore(connection))
  {
    // See https://github.com/esri/arcgis-pro-sdk/wiki/ProConcepts-3D-Analyst-Data#working-with-tin-data
    TinDataset tinDataset2 = dataStore.OpenDataset<ArcGIS.Core.Data.Analyst3D.TinDataset>(Path.GetFileName(tinPath2));
    numNodes = tinDataset2.GetNodeCount(); // numNodes = 31
  }

  // The edits still show up in the original TIN while it is in memory, but if you open it
  // again you will see that it only has the edits that were saved before SaveAs was called.
  numNodes = tinDataset.GetNodeCount(); // numNodes = 31
  var connection2 = new FileSystemConnectionPath(new Uri(Path.GetDirectoryName(tinPath)), FileSystemDatastoreType.Tin);
  using (FileSystemDatastore dataStore = new FileSystemDatastore(connection))
  {
    // See https://github.com/esri/arcgis-pro-sdk/wiki/ProConcepts-3D-Analyst-Data#working-with-tin-data
    tinDataset = dataStore.OpenDataset<ArcGIS.Core.Data.Analyst3D.TinDataset>(Path.GetFileName(tinPath));
    numNodes = tinDataset.GetNodeCount(); // numNodes = 11
  }
}