public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) { var parameterString = parameter.ToString(); bool isTrue = false; if (parameterString.Contains("?")) { var compareValue = parameterString.Substring(0, parameterString.IndexOf("?", StringComparison.Ordinal)); isTrue = values.All(i => i?.ToString() == compareValue); } else { isTrue = values.Skip(1).All(i => i?.ToString() == values[0]?.ToString()); } return(ConverterHelper.Result <bool?>(isTrue, i => i, targetType, parameter)); }