AdMob - "Ad wasn't ready" error with real unit ID (Swift) - ios

Question

I try to setup interstitial ads in my app. If I use a test unit ID, ad shows fine, but if I try to use the real unit ID, I see the error "Ad wasn't ready". What I do wrong? Thank for any help!
My code:
import UIKit
import GoogleMobileAds
class ViewController: UIViewController {
var interstitial: GADInterstitial!
override func viewDidLoad() {
super.viewDidLoad()
interstitial = createAndLoadInterstitial()
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
if self.interstitial.isReady {
self.interstitial.present(fromRootViewController: self)
} else {
print("Ad wasn't ready")
}
}
}
func createAndLoadInterstitial() -> GADInterstitial {
let interstitial = GADInterstitial(adUnitID: "AdMob Real Unit ID")
interstitial.delegate = self
let request = GADRequest()
GADMobileAds.sharedInstance().requestConfiguration.testDeviceIdentifiers = ["my device ID from console"]
interstitial.load(request)
return interstitial
}
}
extension ViewController: GADInterstitialDelegate {
func interstitialDidDismissScreen(_ ad: GADInterstitial) {
interstitial = createAndLoadInterstitial()
}
}
Console:

Answer 1

Launching interstitial ad immediately after page load is disallowed.
Refer Disallowed Interstitial implementation policy https://support.google.com/admob/answer/6201362?hl=en
A common issue is that even though you may intend for the ad to load
in between page content, the ad itself appears shortly after a new
page of content has loaded due to carrier latency. To prevent this
from happening, we recommend you pre-load the interstitial in advance.
To learn more about how to pre-load your interstitial ad, please
follow the AdMob Interstitial Ad developer guidelines for apps
developed for Android and iOS.
Only load the ad on viewDidLoad () https://developers.google.com/admob/ios/interstitial
class ViewController: UIViewController {
var interstitial: GADInterstitial!
override func viewDidLoad() {
super.viewDidLoad()
interstitial = GADInterstitial(adUnitID: "ca-app-pub-3940256099942544/4411468910")
let request = GADRequest()
interstitial.load(request)
}
}
and then Interstitials should be displayed during natural pauses in the flow of an app. Between levels of a game is a good example, or after the user completes a task.
#IBAction func doSomething(_ sender: AnyObject) {
...
if interstitial.isReady {
interstitial.present(fromRootViewController: self)
} else {
print("Ad wasn't ready")
}
}

Answer 2

Solved:
To display your ad units, your AdMob account must be verified.
You must see message in the Google AdMob Console:
Your account is approved
Congratulations! We've verified your account information and your ad serving is enabled.