修改
protected void inspectorclass()
{
var featLayer = MapView.Active.GetSelectedLayers().First() as FeatureLayer;
Int64 oid = 1;
#region inspectorclass
QueuedTask.Run(() =>
{
var insp = new Inspector();
insp.Load(featLayer, oid);
//get the shape of the feature
var myGeometry = insp.Shape;
//get an attribue value by name
var propValue = insp["tfh"];
MessageBox.Show(propValue.ToString());
//set an attribute value by name
insp["m"] = "42";
//perform the edit
var op = new EditOperation();
op.Name = "Update parcel";
op.Modify(insp);
op.Execute();
});