Does the Yii framework contain a function that can make a string usable in a URL or filename ?
For example: Health+%26+Safety+franchises
= health-safety-franchises
So something similar to: https://docs.djangoproject.com/en/dev/ref/templates/builtins/#slugify
Have a look to this class into yii2
https://github.com/yiisoft/yii2/blob/master/framework/behaviors/SluggableBehavior.php
and see how it use this library http://www.yiiframework.com/doc-2.0/yii-helpers-inflector.html the slug method
You can add a behaviour to a model for that - this plugin will do the hard work for you.
It is still not completely clear what you are trying to achieve exactly. If you want to use a string that contains characters that are not supported by the browser then you should look into php functions that can do this for you.
Perhaps http://php.net/manual/en/function.urlencode.php (there are more, depends what you need)
If you want to use your own custom encoding then specify what your trying to achieve and I might be able to help.
slugify in Django Converts to lowercase, removes non-word characters (alphanumerics and underscores) and converts spaces to hyphens. Also strips leading and trailing whitespace.
Following are the functions in PHP to carry out same tasks.
You need to define a function in some controller TO use it in Yii