public sealed class Inspector : ArcGIS.Desktop.Framework.Contracts.PropertyChangedBase, System.Collections.Generic.IEnumerable<Attribute>, System.Collections.IEnumerable, System.ComponentModel.INotifyPropertyChanged  

var insp = new Inspector();
insp.LoadSchema(featLayer);
var attrib = insp.Where(a => a.FieldName == "Mineral").First();

attrib.AddValidate(() =>
{
  if (attrib.CurrentValue.ToString() == "Salt")
    return Enumerable.Empty<ArcGIS.Desktop.Editing.Attributes.Attribute.ValidationError>();
  else return new[] { ArcGIS.Desktop.Editing.Attributes.Attribute.ValidationError.Create("Error", ArcGIS.Desktop.Editing.Attributes.Severity.Low) };
});

QueuedTask.Run(() =>
{
  //get selected feature into inspector
  var selectedFeatures = MapView.Active.Map.GetSelection();

  var insp = new Inspector();
  insp.Load(selectedFeatures.ToDictionary().Keys.First(), selectedFeatures.ToDictionary().Values.First());

  //read a blob field and save to a file
  var msw = new MemoryStream();
  msw = insp["Blobfield"] as MemoryStream;
  using (FileStream file = new FileStream(@"d:\temp\blob.jpg", FileMode.Create, FileAccess.Write))
  {
    msw.WriteTo(file);
  }

  //read file into memory stream
  var msr = new MemoryStream();
  using (FileStream file = new FileStream(@"d:\images\Hydrant.jpg", FileMode.Open, FileAccess.Read))
  {
    file.CopyTo(msr);
  }

  //put the memory stream in the blob field and save to feature
  var op = new EditOperation();
  op.Name = "Blob Inspector";
  insp["Blobfield"] = msr;
  op.Modify(insp);
  if (!op.IsEmpty)
  {
    var result = op.Execute(); //Execute and ExecuteAsync will return true if the operation was successful and false if not
  }
});