MainViewController.swift

class MainViewController: UIViewController, ChoosePlanetMoonDelegate {
    @IBOutlet weak var mainPlanetImage: UIImageView!
    @IBOutlet weak var changeButton: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    @IBAction func changeButtonDidTapped(_ sender: Any) {
        let chooseVC = storyboard?.instantiateViewController(identifier: "chooseVC") as! ChooseViewController
        chooseVC.modalPresentationStyle = .fullScreen
        self.present(chooseVC, animated: true, completion: nil)
    }
    
    func didChoosePlanetWith(image: UIImage) {
        mainPlanetImage.image = image
    }
}