Swift - 来自 appDelegate 的 pushViewController，rootViewController.navigationController 为 nil [英] Swift - pushViewController from appDelegate, rootViewController.navigationController is nil

问题描述

在遵循一些指南时遇到问题，特别是http://blog.originate.com/blog/2014/04/22/deeplinking-in-ios/

Having a problem following a few guides, specifically http://blog.originate.com/blog/2014/04/22/deeplinking-in-ios/

我正在设置 url 方案，从另一个应用程序启动该应用程序运行良好，但传入主机或 url 并不能正常工作.我正在为所有视图布局使用故事板和界面构建器.

I'm setting the url scheme and it's working well to launch the app from another app, but passing in the host or url are not working as it seems it should. I'm using storyboards and interface builder for all the view layouts.

指南在 appDelegate 中显示了这个 openURL:

The guide shows this openURL in appDelegate:

-(BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation{
    if([[url host] isEqualToString:@"page"]){
        if([[url path] isEqualToString:@"/page1"]){
            [self.mainController pushViewController:[[Page1ViewController alloc] init] animated:YES];
        }
    return YES;
    }
}

这是我从其他几个来源快速简化的版本，即在 Swift 中从 AppDelegate 获取 ViewController 实例 我跳过目前 url 主机的条件以删除问题中的潜在其他变量.

Here is my version simplified and in swift from a few other sources, ie Get Instance Of ViewController From AppDelegate In Swift I'm skipping the conditional for the url host at the moment to remove potential other variables in the problem.

func application(application: UIApplication, openURL url: NSURL, sourceApplication: String, annotation: AnyObject?) -> Bool {
    var rootViewController = self.window!.rootViewController
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    var profileViewController = mainStoryboard.instantiateViewControllerWithIdentifier("profile") as ProfileViewController

    rootViewController.navigationController.popToViewController(profileViewController, animated: true)

    return true

}

swift 版本导致崩溃:致命错误:在展开可选值时意外发现 nil

The swift version causes a crash: fatal error: unexpectedly found nil while unwrapping an Optional value

好像rootViewController还没有navigationController?

It seems that rootViewController doesn't have a navigationController yet?

推荐答案

在我的例子中，rootViewController 似乎实际上是 UINavigationController 类型，所以在声明中强制转换允许我直接在其上调用 pushToViewController.

It seems that rootViewController actually is of type UINavigationController in my case, so casting it on declaration allowed me to call pushToViewController directly on it.

func application(application: UIApplication, openURL url: NSURL, sourceApplication: String, annotation: AnyObject?) -> Bool {
    let rootViewController = self.window!.rootViewController as! UINavigationController
    let mainStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let profileViewController = mainStoryboard.instantiateViewController(withIdentifier: "InstructionVC") as! InstructionVC
    rootViewController.pushViewController(profileViewController, animated: true)
    return true

}

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