Swift 获取当前显示的视图控制器

 // MARK: - 查找顶层控制器、
 // 获取顶层控制器 根据window
func getTopVC() -> (UIViewController?) {
    var window = UIApplication.shared.keyWindow
    //是否为当前显示的window
    if window?.windowLevel != UIWindowLevelNormal{
      let windows = UIApplication.shared.windows
      for  windowTemp in windows{
        if windowTemp.windowLevel == UIWindowLevelNormal{
          window = windowTemp
          break
      }
    }
  }
  let vc = window?.rootViewController
  return getTopVC(withCurrentVC: vc)
 }
  ///根据控制器获取 顶层控制器
func getTopVC(withCurrentVC VC :UIViewController?) -> UIViewController? {
 if VC == nil {
    print("🌶： 找不到顶层控制器")
    return nil
}
 if let presentVC = VC?.presentedViewController {
    //modal出来的 控制器
    return getTopVC(withCurrentVC: presentVC)
}else if let tabVC = VC as? UITabBarController {
  // tabBar 的跟控制器
    if let selectVC = tabVC.selectedViewController {
      return getTopVC(withCurrentVC: selectVC)
    }
    return nil
} else if let naiVC = VC as? UINavigationController {
  // 控制器是 nav
    return getTopVC(withCurrentVC:naiVC.visibleViewController)
  } else {
  // 返回顶控制器
  return VC
  }
}

方法调用:let vc:UIViewController = getTopVC()!
判断控制器的类型

  if vc .isKind(of: UserVC.classForCoder()) {
    print("当前控制器是 = UserVC")
}