Soulja Boy Whips his hair? LOL

So from Soulja Boy he states that he wrote Willow Smith's smash hit"Whip My Hair" At first I thought that somebody had to write for her but then I listen to the lyrics and was like she could've wrote this song. Also in the song Willow says "Hop up out the bed turn my swag on" which is one of Soulja Boy's quotes and songs. So that kind-of gave a hint to who wrote the song.