iOS 侧滑返回首页

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    
    guard let rootVC = navigationController?.viewControllers.first,
          let spVC = navigationController?.viewControllers.filter({ $0 is SPViewController }).first else { return }
    
    navigationController!.viewControllers = [rootVC, spVC]
}