PHP Returning an object from a function

My problem is this (In PHP):

I have three classes,

Class cls1 {
    public function myfunc() {

    }
}
Class cls2 {
    private $_obj1; //type of cls1
    ...

    public function getObj1() {
        return $_obj1;
    }
}

Class cls3 {
    ...
    public function getMyFunc() {
        $temp = new cls2();
        $temp->getObj1()->myfunc(); //THIS IS NOT WORKING.

        //PHP Throws an error like : Fatal error: Call to a member function getId() on a non-object in xyz.php on line 125.
    }
}

I cannot reach cls1's function from cls3 through the way cls2.

How can I implement it?

NOTE: I wrote this basic code to show the problem. Do not consider about syntax errors.

Answer

Object1 hasn't been instantiated yet.

Class cls1 {
    public function myfunc() {

    }
}
Class cls2 {
    private $_obj1; //type of cls1

    ...
    public function getObj1() {
        if(!$this->$_obj1 instanceof cls1) {
            $this->_obj = new cls1();
        }
        return $_obj1;
    }
}

Class cls3 {

    ...
    public function getMyFunc() {
        $temp = new cls2();
        $temp->getObj1()->myfunc(); //THIS IS NOT WORKING.
    }
}