banner_unity.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Advertisements;

public class BannerAdManager : MonoBehaviour {

    #if UNITY_IOS
    private string gameId = "1234567";
    #elif UNITY_ANDROID
    private string gameId = "1234568";
    #endif

    public string placementId = "my_banner";
    public bool testMode = true;

    void Start () {
        Advertisement.Initialize (gameId, testMode);
        StartCoroutine (ShowBannerWhenReady ());
    }

    IEnumerator ShowBannerWhenReady () {
        while (!Advertisement.IsReady (placementId)) {
            yield return new WaitForSeconds (0.5f);
        }
        Advertisement.Banner.SetPosition(BannerPosition.BOTTOM_CENTER);
        Advertisement.Banner.Show (placementId);
    }
}