sd checkbox directive

gistfile1.js

<input type="checkbox" ng-model="item.selected" sd-custombox />

directive.js:

return {
    require: '?ngModel',
    link: function($scope, element, attrs, ngModel) {
        element.click(function() {
            $scope.$apply(function() {
                ngModel.$serViewValue(!ngModel.$getViewValue());
            });
        });

        // init
        ngModel.$render(function() {
           element.attr('checked', ngModel.$getViewValue());
        });
    }
}