how i load Appodeal ad to load Ad in ios swift as RewardVideoAd?

Question

I set all steps what given in Appodeal documentation in iOS Swift but Ad does't load. Now i use RewardVideoAd from this documentation

this is AppDelegate Class

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    Appodeal.setAutocache(false, types: AppodealConstants.adTypes)
    Appodeal.setLogLevel(AppodealConstants.logLevel)
    Appodeal.setTestingEnabled(AppodealConstants.testMode)
    Appodeal.setInitializationDelegate(self)
    Appodeal.initialize(withApiKey: AppodealConstants.key, types: AppodealConstants.adTypes)
    return true
}

this is my ViewController class

import Appodeal

class MOStoreVC: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        Appodeal.cacheAd(.rewardedVideo)
        Appodeal.setRewardedVideoDelegate(self)

        guard Appodeal.isInitialized(for: .rewardedVideo), Appodeal.canShow(.rewardedVideo, forPlacement: Helpers.placement) else {
            return
        }

        Appodeal.showAd(.rewardedVideo,
                        forPlacement: Helpers.placement,
                        rootViewController: self)
     }
}