@Override
 public void onDestroy() {
   if (mBannerView != null) {
     mBannerView.destroy();
   }
   if (mMrectView != null) {
     mMrectView.destroy();
   }
   super.onDestroy();
 }
  @Override
  public void onDestroyView() {
    super.onDestroyView();

    if (mMoPubView != null) {
      mMoPubView.destroy();
      mMoPubView = null;
    }
  }