MVC.CheckBoxExtensions.cs

    public static class CheckBoxExtensions
    {
        public static MvcHtmlString CheckBoxFor<TModel>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, int>> expression, int value)
        {
            if (expression == null)
            {
                throw new ArgumentNullException("expression");
            }
            ModelMetadata modelMetadata = ModelMetadata.FromLambdaExpression<TModel, int>(expression, htmlHelper.ViewData);
            string modelName = ExpressionHelper.GetExpressionText(expression);

            TagBuilder tagBuilder = new TagBuilder("input");
            tagBuilder.MergeAttribute("type", "checkbox", true);
            tagBuilder.MergeAttribute("name", modelName, true);
            tagBuilder.MergeAttribute("value", value.ToString(), true);

            if (modelMetadata.Model != null && (int)modelMetadata.Model == value)
            {
                tagBuilder.MergeAttribute("checked", "checked", true);
            }

            return new MvcHtmlString(tagBuilder.ToString());
        }

        public static MvcHtmlString CheckBoxFor<TModel, T>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, T>> expression, string value) where T : struct
        {
            if (expression == null)
            {
                throw new ArgumentNullException("expression");
            }
            ModelMetadata modelMetadata = ModelMetadata.FromLambdaExpression<TModel, T>(expression, htmlHelper.ViewData);
            string modelName = ExpressionHelper.GetExpressionText(expression);

            TagBuilder tagBuilder = new TagBuilder("input");
            tagBuilder.MergeAttribute("type", "checkbox", true);
            tagBuilder.MergeAttribute("name", modelName, true);
            tagBuilder.MergeAttribute("value", value.ToString(), true);

            if (modelMetadata.Model != null && (modelMetadata.Model.ToString() == EnumHelper.GetEnumByKey(typeof(T), value).ToString()))
            {
                tagBuilder.MergeAttribute("checked", "checked", true);
            }

            return new MvcHtmlString(tagBuilder.ToString());
        }
    }