I heard on espn they said that he is second in the league for most game winning shots behind d-wade
This sounds highly misleading so I looked up some GSTankers stats.
This year they have had 1 game where they had a "game winning shot". That was this game against OKC and Iggy hit the winning shot. The season is very young and not that many game winning shot chances have heppened yet.
So it is entirely plausible that Iggy is in second with 1 game winning shot. Did you perhaps mean amoung active players over their careers? Now that would be interesting.