First you need to create a request and execute it

self.request = [BDMBannerRequest new];
    self.request.adSize = BDMBannerAdSize320x50;
    [self.request performWithDelegate:self];

After polling, you need to save the bid request ([BDMRequestStorage.shared saveRequest:request];)

#pragma mark - BDMRequestDelegate

- (void)request:(BDMRequest *)request completeWithInfo:(BDMAuctionInfo *)info {
    // After request complete loading application can lost strong ref on it
    // BidMachineFetcher will capture request by itself
    self.request = nil;
    // Save request for bid
    [BDMRequestStorage.shared saveRequest:request];
    // Here we define which Admob ad should be loaded
    [self makeRequest];

Then you can create an Admob object and load it

- (void)makeRequest {

    self.bannerView = [[GADBannerView alloc] initWithAdSize:kGADAdSizeBanner];
    self.bannerView.delegate = self;
    self.bannerView.adUnitID = @UNIT_ID;
    self.bannerView.rootViewController = self;
    self.bannerView.translatesAutoresizingMaskIntoConstraints = YES;
    self.bannerView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    GADRequest *request = [GADRequest request];
    [self.bannerView loadRequest:request];