Swing out from the platform and turn around. Swing back to the platform and then back out to the frontend again. As you approach the peak, bring your legs up in front and pass one of them between your hands as if getting into a Split position. Immediately let go of the Split position with a half twist to make the catch. You will probably find that you don't have time to make a very beautiful Split position.
You can find out more about this trick in my books:
Thanks to the team at Circus Arts Australia for providing a video for this page.