## 方法 设置内置构建器实例作为选项内容： > 注: 该实例必须实现 `builder\base\ViewBuilderInterface`该接口, 如: `FormBuilder`/`FormStepBuilder`/`ListBuilder`/`TreeBuilder`/`TreeTableBuilder`/`TableBuilder`等 ```php $builder = $tabItem->builder($viewBuilder); ``` 切换时, 重载选项内容： ```php $builder->switchReload(); ``` 设置选项卡唯一ID：(默认: 程序自动生成) ```php $builder->id($idStr); ``` 初始化时, 默认选中当前选项卡： ```php $builder->selected(); ```