src/TaggableBehavior.php
public function addTags($tags)
    {
        $this->_tagsList = array_unique(array_merge($this->getTagValues(), $this->parseTags($tags)));
        $this->updateOwnerTags();
    }
public function addTags($tags)
    {
        $this->_tagsList = array_unique(array_merge($this->getTagValues(), $this->parseTags($tags)));
        $this->updateOwnerTags();
    }
Add tags
@param string|string[] $tags list of tags added to the current. If specified as a string, the tags must be separated by commas