use yii\helpers\Inflector; $camelCaseString = 'thisIsCamelCase'; // Outputs 'this-is-camel-case' echo Inflector::camel2id($camelCaseString, '-');In the above code, we use the Inflector class from the Yii.helpers package to convert a camelCase string to an underscore-separated string using dash separator. Overall, Yii.helpers Inflector is a useful package for handling string transformations in a Yii PHP framework application.