ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Desktop.Mapping Namespace / GroupLayer Class / SetUseSymbolLayerDrawing Method
Set to true to use symbol layer drawing
Example Version

SetUseSymbolLayerDrawing Method (GroupLayer)
Sets whether Symbol Layer Drawing will be used on the group layer or not. This method must be called on the MCT. Use QueuedTask.Run.
Syntax
public void SetUseSymbolLayerDrawing( 
   bool useSLD
)

Parameters

useSLD
Set to true to use symbol layer drawing
Exceptions
ExceptionDescription
This method or property must be called within the lambda passed to QueuedTask.Run.
SLD has not been added to this layer or a parent
SLD is being controlled by a parent group layer
Remarks
Calling SetUseSymbolLayerDrawing(useSLD) on a group layer that does not have SLD added, or on a group layer that is part of a parent group layer using SLD, will throw an System.InvalidOperationException. Use HasSymbolLayerDrawingAdded to determine if the group layer has SLD added or participates in a parent group layer with SLD added.
Example
Enable/Disable SLD
QueuedTask.Run(() =>
{
  //A layer may have SLD added but is not using it
  //HasSymbolLayerDrawingAdded returns a tuple - to check
  //the layer has SLD (not its parent) check addedOnLayer
  if (featLayer.HasSymbolLayerDrawingAdded().addedOnLayer)
  {
    //the layer has SLD but is the layer currently using it?
    //GetUseSymbolLayerDrawing returns a tuple - useOnLayer for 
    //the layer (and useOnParent for the parent layer)
    if (!featLayer.GetUseSymbolLayerDrawing().useOnLayer)
    {
      //enable it
      featLayer.SetUseSymbolLayerDrawing(true);
    }
  }

  //Enable/Disable SLD on a layer parent
  if (featLayer.HasSymbolLayerDrawingAdded().addedOnParent)
  {
    //check parent...this can be recursive
    var parent = GetParentLayerWithSLD(featLayer.Parent as GroupLayer);
    if (parent.GetUseSymbolLayerDrawing().useOnLayer)
      parent.SetUseSymbolLayerDrawing(true);
  }
  /*
   * 
   //Recursively get the parent with SLD
   public GroupLayer GetParentLayerWithSLD(GroupLayer groupLayer) 
   {
     if (groupLayer == null)
       return null;
     //Must be on QueuedTask
     var sld_added = groupLayer.HasSymbolLayerDrawingAdded();
     if (sld_added.addedOnLayer)
       return groupLayer;
     else if (sld_added.addedOnParent)
       return GetParentLayerWithSLD(groupLayer.Parent as GroupLayer);
     return null;
   }
  */
});
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.
See Also