ios - 快速获取以前的 UIViewController

Question

我想获取之前的viewController。

当我从 navigation 菜单中选择任何行时，我有 2 个 UIViewControllers 和 navigationMenu 我想从打开菜单的位置获取 UIViewController 以移动到第二个 UIViewController。

我想知道在这种情况下如何获取以前的 UIViewController

我试过了，但计数返回 nil:

 let n: Int! = self.navigationController?.viewControllers.count
 print(n)
 let myUIViewController = self.navigationController?.viewControllers[n-2] as! UIViewController

编辑:-

打开菜单代码

  let menuButton = UIBarButtonItem.init(title :"open", style: .plain, target: self.revealViewController(), action: #selector(SWRevealViewController.revealToggle(_:)))
    navigationItem.leftBarButtonItem = menuButton

Answer 1

这是获取之前的viewController的方法，查看注释解释:

// get all the viewControllers to start with
if let controllers = self.navigationController?.viewControllers {
    // iterate through all the viewControllers
    for (index, controller) in controllers.enumerated() {
        // when you find your current viewController
        if controller == self {
            // then you can get index - 1 in the viewControllers array to get the previous one
            let myUIViewController = controllers[index-1]
            print(controllers[index-1])
        }
    }
}