Listen for an animation to complete

I'm trying to perform an action after my animation finishes. I tried adding a statusListener but that is not working for me. My code looks like this:

  @override
  void initState() {
    super.initState();
    _controller = new AnimationController(
      duration: new Duration(milliseconds: 500),
      vsync: this,
    )..addStatusListener((AnimationStatus status) {
      print("Going");
      if (status.index == 3 && spins > 0) { // AnimationStatus index 3 == completed animation
        _controller.duration = new Duration(milliseconds: speed - 50);
        _controller.forward(from: _controller.value == null ? 0.0 : 1 - _controller.value);
        spins--;
        print(speed);
      }
    });
  }

The print(Going); never gets executed but my animation does end. What is going wrong?

///---Edit---///

I'm using an AnimatedBuilder, that part of the code looks like this:

child: new AnimatedBuilder(
  animation: _controller,
  child: new Image.network(widget.url),
  builder: (BuildContext context, Widget child) {
    return new Transform.rotate(
      angle: _controller.value * 2.0 * math.PI,
      child: child,
    );
  },
),