How do I simulate a yoyo effect?

Hello, I'm making a game where the player character has stretch powers (think Mr. Fantastic), and one of the attacks in a stretch punch that sort of works like a yoyo. Originally I had issues implementing this and everything I tried didn't seem to work (custom movement, physics) until I tried this:

The method in the above link uses a for loop to simulate the yoyo effect. It works but the arm always stretches at fixed length. I want to change so that if the fist (ball) was the come in contact with barrier it would immediately contract.

Illustration of what I'm trying to achieve:

http://i.imgur.com/SfZaLnK.png

Screenshot of For Loops:

http://i.imgur.com/mMYeYAU.png

Project DL Link:

https://dl.dropboxusercontent.com/u/4173094/StretchPunchDemo.zip

Try this:

https://dl.dropboxusercontent.com/u/542 ... /yoyo.capx

Nice example.

On Angvik game there are professional weapons using this method.

Try this:

https://dl.dropboxusercontent.com/u/542 ... /yoyo.capx

Thanks! Was exactly what I was looking for.