facebook Audience Network无法显示横幅广告和在Audience Network中无效的横幅广告

Question

import UIKit
import FBAudienceNetwork

class bannerVC: UIViewController , FBAdViewDelegate  {
    var bannerADView:FBAdView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    
    func loadFacebookbanner() {
                
        bannerADView = FBAdView(placementID: "..........", adSize: kFBAdSizeHeight50Banner, rootViewController: self)
        bannerADView.frame = CGRect(x: 0, y: 50, width: UIScreen.main.bounds.size.width, height: 50)
        bannerADView.delegate = self
        bannerADView.isHidden = true
        self.view.addSubview(bannerADView)
        bannerADView.loadAd()
    }

    func adViewDidLoad(_ adView: FBAdView) {
        bannerADView.isHidden = false
        print("didLoad")
    }

    func adView(_ adView: FBAdView, didFailWithError error: Error) {
        print(error)
    }
               
    func adView(adView: FBAdView, didFailWithError error: NSError) {
        print(error)
    }
    
    func adViewDidClick(adView: FBAdView) {
        print("Did tap on ad view")
    }

    func adViewDidFinishHandlingClick(_ adView: FBAdView) {
        print("Banner ad did finish click handling")
    }

    func adViewWillLogImpression(_ adView: FBAdView) {
        print("Banner ad impression is being captured")
    }
    
    @IBAction func btnShowAds(_ sender: UIButton) {
        loadFacebookbanner()
    }
}