Please tell me how to set up a two-dimensional array of images.

@IBOutlet varmainImage:UIImageView!
variableListArray:Array<UIImage>=[ ]
var number : Int!// Number // Respondent modification delivered from previous page

override func viewDidLoad(){
    super.viewDidLoad()

    // UIImage
    let image0:UIImage!=UIImage(named: "img.png")
    let image1: UIImage!= UIImage(named: "img.png") // Provisional

    // ImageListArray
    imageListArray.append(image0)
    imageListArray.append(image1)

    mainimage.image=imageListArray [number]
}