Swift 动态转换失败 UIPageViewController [英] Swift dynamic cast failed UIPageViewController

问题描述

我试图将我的 window.rootViewController 转换为 UIPageViewController，但是每当我访问我定义的类属性时，它都会因 swift 动态转换失败 而崩溃.我的故事板有一个 UIPageViewController 是初始场景.

I am trying to cast my window.rootViewController as a UIPageViewController but anytime I access the class property which I defined it blows up with swift dynamic cast failed. My storyboard has a UIPageViewController is the initial scene.

PageViewController 只是 UIPageViewController 的一个子类

PageViewController is just a subclass of UIPageViewController

class AppDelegate: UIResponder, UIApplicationDelegate, UIPageViewControllerDataSource {

    var window: UIWindow!

    var pageViewController: PageViewController {
        return window.rootViewController as PageViewController
    }

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {

        pageViewController.dataSource = self

        return true
    }

 }

推荐答案

主要问题实际上是因为我正在继承 UIPageViewController 我必须将自定义类添加到我的故事板内的 ViewController.起初我想，由于 PageViewController 是一个 UIPageViewController，而且我只是将 rootViewController 转换为一个 PageViewController，它应该可以工作.通过添加自定义类，它解决了我的问题.

The main issue actually was because I was subclassing UIPageViewController I had to add the custom class to the ViewController inside my storyboard. At first I figured that since PageViewController is a UIPageViewController, and I am just casting the rootViewController to a PageViewController, it should've of worked. By adding the custom class it fixed my problem.

我还通过非子类化进行了测试，它无需指定自定义类即可工作.

I also tested by not subclassing, it worked with out specifying a custom class.

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