How to create a UIButton with a black gradient for iPhone?

I want to create a UIButton with the normal black gradient theme in iOS. I've looked at the documentation and can't seem to figure out how to do this. When I create the button, I get a rounded rect button with no color.

Here is my code:

UIButton* leagueTeamButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];

Any suggestions on how I can add the standard themed black gradient to the button?