Displaying images with action in swift?

I'm a kind new to Xcode/swift, I am trying to build a game where 5 pics need to selected randomly, So my code looks something like that: ()

var options = ["1.png","2.png","3.png","4.png","4.png"]

@IBAction func option1(sender: AnyObject) {

    var randomNumber = Int(arc4random_uniform(5))
    **iphoneChoise.image(options[randomNumber])**   /*This line is not correct*/     

} please help!