使用Swift和iOS 8 Storyboard登录屏幕

Question

我在处理iOS应用程序的登录流程时遇到了很多麻烦。 我想要实现的故事板的图像如下

我正在尝试实现一个可选的登录屏幕，该屏幕仅在用户首次打开应用程序并且尚未登录时显示。目前，我将Tab Bar Controller设置为根视图控制器。 但是，我无法弄清楚如何处理这些视图控制器之间的交换。

我试图用以下代码简单地按下登录屏幕。 但是，它不起作用。 我相信标签栏控制器不允许推送新视图控制器的问题。

    func application(application: UIApplication, didFinishLaunchingWithOptions  launchOptions: [NSObject: AnyObject]?) -> Bool {
    //stuff

    if userLoggedIn {
        // Do nothing
    } else {
        //get access to login view
        var storyboard = UIStoryboard(name: "Main", bundle: nil)
        var viewController =    storyboard.instantiateViewControllerWithIdentifier("signupView") as UIViewController;

        // Then push login view
        var rootViewController = self.window!.rootViewController as UITabBarController;
        rootViewController.pushViewController(viewController, animated: true)
    }

    // Override point for customization after application launch.
    return true
}

有没有办法在不推入导航控制器的情况下切换视图控制器？ 任何关于如何处理这种登录流程的建议将不胜感激。

Answer 1

我通过“LaunchViewController”来实现这个目的，它确定它是否应该呈现Login视图或主导航控制器。

将启动视图标记为故事板中的初始视图，并在其中编写逻辑以确定要呈现的内容。 对于用户来说，该过程通常非常快速且不明显。

更新 ：

正如我在评论中所提到的，我走的是另一个方向。 现在在App Delegate的application(application:didFinishLaunchingWithOptions:)方法中，我执行必要的逻辑来确定哪个视图应该是rootViewController并使用以下内容将其设置在那里。

extension AppDelegate {

    enum LaunchViewController {
        case Login, Dashboard

        var viewController: UIViewController {
            switch self {
            case .Login: return StoryboardScene.Login.LoginScene.viewController()
            case .Dashboard: return StoryboardScene.Dashboard.initialViewController()
            }
        }

        /// Sets `UIWindow().rootViewController` to the appropriate view controller, by default this runs without an animation.
        func setAsRootviewController(animated animated: Bool = false) {
            let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
            let window = appDelegate.window!
            let launchViewController = viewController

            log.info?.message("Setting \(launchViewController.dynamicType) as rootViewController")
            if let rootViewController = window.rootViewController where rootViewController.dynamicType != launchViewController.dynamicType && animated {
                let overlayView = UIScreen.mainScreen().snapshotViewAfterScreenUpdates(false)
                launchViewController.view.addSubview(overlayView)

                UIView.animateWithDuration(0.3, animations: {
                    overlayView.alpha = 0.0
                    },
                    completion: { _ in
                        overlayView.removeFromSuperview()
                });
            }

            window.rootViewController = launchViewController
            window.restorationIdentifier = String(launchViewController.dynamicType)

            if window.keyWindow == false {
                window.makeKeyAndVisible()
            }
        }
    }
}

请注意， StoryboardScene不是默认类型，我使用https://github.com/AliSoftware/SwiftGen来生成它。

My App Delegate方法看起来像这样。

if window == nil {
    window = UIWindow(frame: UIScreen.mainScreen().bounds)
}

if isRestoringState == false {
    if let _ = lastUsedAccount {
        LaunchViewController.Dashboard.setAsRootviewController()
    } else {
        LaunchViewController.Login.setAsRootviewController()
    }
}

使用Logout方法更新注释

func handleLogout(notification: NSNotification) {
  LaunchViewController.Login.setAsRootviewController(animated: true)
  lastUsedAccount = nil
}

Answer 2

这是我做的，它工作正常：

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    if (!AppData.sharedInstance.loggedIn) {
        let signInNavigation = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle()).instantiateViewControllerWithIdentifier("SignInNavigationControllerIdentifier") as? UINavigationController
        self.window!.rootViewController = signInNavigation;
    }
    return true
}

Answer 3

为LoginViewController设置Is Initial View Controller 。

从AppDelegate.swift删除并将其放在LoginViewController 。

if userLoggedIn {
        // Do nothing
    } else {
        //get access to login view
        var storyboard = UIStoryboard(name: "Main", bundle: nil)
        var viewController =    storyboard.instantiateViewControllerWithIdentifier("signupView") as UIViewController;

        // Then push login view
        var rootViewController = self.window!.rootViewController as UITabBarController;
        rootViewController.pushViewController(viewController, animated: true)
    }

运行您的项目。