获取最上面的UIViewController

你想要的 visibleViewController :

当前可见的视图可以属于导航堆栈顶部的视图控制器,也可以属于以模式显示的视图控制器。

NSArray *viewContrlls=[[self navigationController] viewControllers];

[viewContrlls lastObject];

UIViewController's 子类。同时,您可以通过自定义“集合”控制器(如侧菜单)扩展此方法的功能。

extension UIWindow {

  var visibleViewController: UIViewController? {
    guard let rootViewController = rootViewController else {
      return nil
    }
    return visibleViewController(for: rootViewController)
  }

  private func visibleViewController(for controller: UIViewController) -> UIViewController {
    var nextOnStackViewController: UIViewController? = nil
    if let presented = controller.presentedViewController {
      nextOnStackViewController = presented
    } else if let navigationController = controller as? UINavigationController,
      let visible = navigationController.visibleViewController {
      nextOnStackViewController = visible
    } else if let tabBarController = controller as? UITabBarController,
      let visible = (tabBarController.selectedViewController ??
        tabBarController.presentedViewController) {
      nextOnStackViewController = visible
    }

    if let nextOnStackViewController = nextOnStackViewController {
      return visibleViewController(for: nextOnStackViewController)
    } else {
      return controller
    }
  }

}