void AddNewItem() { var value = "foo"; var jsonDate = DateTime.UtcNow.ToString("O"); var vals = NSDictionary.FromObjectsAndKeys( new NSObject[] { new NSString(value), NSNumber.FromBoolean(false), new NSString(jsonDate) }, new NSObject[] { new NSString("text"), new NSString("check"), new NSString("created_at") } ); var doc = database.CreateUntitledDocument(); NSError error; var result = doc.PutProperties(vals); if (result == null) { throw new ApplicationException("failed to put props"); } }