How get code in viewDidLoad to act like a button click on RadioButton?

Overview, I have 3 radiobuttons( 1-Goat, 2-Horse, 3-Cow).I read data from file for one person. If person had selected "Horse", I want the radiobutton to be selected.
All 3 radiobuttons call

-(void)radiobuttonselected:(id)sender{
....
}
How can I call radiobuttonselected, from viewDidLoad, and pass it a "2" so that the "Horse" will be selected?
I'm new to ios. Code sample would be great.

Suggestions?

TIA
Steve