src/Models/ElementModel.php
public function saveProps($selected = [])
    {
        $propertyValues = $this->constructPropertyValuesForSave($selected);
        if (empty($propertyValues)) {
            return false;
        }

        $bxMethod = empty($selected) ? 'setPropertyValues' : 'setPropertyValuesEx';
        static::$bxObject->$bxMethod(
            $this->id,
            static::iblockId(),
            $propertyValues
        );

        return true;
    }
public function saveProps($selected = [])
    {
        $propertyValues = $this->constructPropertyValuesForSave($selected);
        if (empty($propertyValues)) {
            return false;
        }

        $bxMethod = empty($selected) ? 'setPropertyValues' : 'setPropertyValuesEx';
        static::$bxObject->$bxMethod(
            $this->id,
            static::iblockId(),
            $propertyValues
        );

        return true;
    }
Save props to database.
If selected is not empty then only props from it are saved.

@param array $selected

@return bool