Swing out and back to the platform. Make a very small set at the platform and break just later than for a swing. Allow your legs to come forwards again and then sweep back again just before the peak so that you rise up vertically (as if standing up). Let go at the peak to catch.
You can find out more about this trick in my books:
Thanks to Alain, Fred and Fly'n Fit for providing a video for this page.