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

问题描述

按照一些指南遇到问题，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，它可以很好地从另一个应用程序启动应用程序，但传递主机或网址似乎不应该工作。我正在使用故事板和界面构建器来处理所有视图布局。

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.

该指南在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;
    }
}

这是我的版本简化并快速从一些其他来源，即
从Swift中的AppDelegate获取ViewController的实例我正在跳过url主机的条件，以删除问题中潜在的其他变量。

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：在解包可选值时意外发现nil

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

似乎rootViewController还没有navigationController？

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

推荐答案

在我的情况下，似乎rootViewController实际上是UINavigationController类型，所以在声明中将它转换为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 = UIStoryboard(name: "Main", bundle: nil)
        let profileViewController = mainStoryboard.instantiateViewController(withIdentifier: "InstructionVC") as! InstructionVC
        rootViewController.pushViewController(profileViewController, animated: true)
    return true

}

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