ArcGIS Pro二次开发-图层标注

 if (MapView.Active.GetSelectedLayers().Count != 1)
            {
                ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show("One feature layer must be selected in the Contents pane. Exiting...", "Info");
                return;
            }

            var lyr = MapView.Active.GetSelectedLayers().First() as FeatureLayer;


            if (lyr == null) return;
            QueuedTask.Run(() =>
            {
                //Get the layer's definition
                //community sample Data\Admin\AdminSample.aprx
                var lyrDefn = lyr.GetDefinition() as CIMFeatureLayer;
                if (lyrDefn == null) return;
                //Get the label classes - we need the first one
                var listLabelClasses = lyrDefn.LabelClasses.ToList();
                var theLabelClass = listLabelClasses.FirstOrDefault();
                //set the label class Expression to use the Arcade expression
                theLabelClass.Expression = "return $feature.gisoracleid + TextFormatting.NewLine + $feature.objectid;";
                //Set the label definition back to the layer.
                lyr.SetDefinition(lyrDefn);
                lyr.SetLabelVisibility(true);
            });