DrawerController的iOS状态恢复问题

Question

I have an app written in Swift 3.1, using Xcode 8.3.3.

I am currently trying to implement state preservation/restoration.

To do this I have implemented shouldSaveApplicationState and willFinishLaunchingWithOptions methods in AppDelegate.swift and set to return true :

// AppDelegate.swift
// STATE RESTORATION CALLBACKS

func application(_ application: UIApplication, shouldSaveApplicationState coder: NSCoder) -> Bool {
    debug_print(this: "shouldSaveApplicationState")
    return true
}
func application(_ application: UIApplication, shouldRestoreApplicationState coder: NSCoder) -> Bool {
    debug_print(this: "shouldRestoreApplicationState")
    restoringState = true
    return true
}

func application(application: UIApplication, willFinishLaunchingWithOptions launchOptions: [NSObject : AnyObject]?) -> Bool {
    debug_print(this: "willFinishLaunchingWithOptions")
    return true
}

I've also provided restoration IDs for all involved viewcontrollers and navigationcontrollers.

I'm using a 3rd party library to handle side drawer navigation container ( https://github.com/sascha/DrawerController ). The initial viewcontroller is set programmatically inside the didFinishLaunchingWithOptions method, see below.

// AppDelegate.swift
var centerContainer: DrawerController?

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let centerViewController =   mainStoryboard.instantiateViewController(withIdentifier: "RootViewControllerNav") as! UINavigationController 
    let leftViewController = mainStoryboard.instantiateViewController(withIdentifier: "SideDrawerViewController") as! UITableViewController

    centerContainer = DrawerController(centerViewController: centerViewController, leftDrawerViewController: leftViewController)

    centerContainer?.restorationIdentifier = "DrawerControllerView"
    window = UIWindow(frame: UIScreen.main.bounds)
    window?.restorationIdentifier = "MainWindow"
    window?.rootViewController = centerContainer
    window?.makeKeyAndVisible()

    return true
}

When app opens and attempts to restore state, it displays the correct viewcontroller (last controller before app closed) temporarily, then once app becomes active it reverts back to the initial viewcontroller.

For example, the following happens:

1. Open app Navigate to the “settings” view via the side menu
2. Navigate to the home screen
3. Stop running xcode and start it again
4. App will open showing settings view, then revert back to home view

Can anyone tell me what is causing this, or where I am going wrong? Let me know if you need any more code examples.

Answer 1

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.

        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let leftSideDrawerViewController = mainStoryboard.instantiateViewController(withIdentifier: "SideDrawerViewController") as! UITableViewController
        let centerViewController = mainStoryboard.instantiateViewController(withIdentifier: "RootViewControllerNav") as! UINavigationController
        let navigationController = UINavigationController(rootViewController: centerViewController)
        navigationController.restorationIdentifier = "navigationControllerKey"
        let leftSideNavController = UINavigationController(rootViewController: leftSideDrawerViewController)
        leftSideNavController.restorationIdentifier = "LeftNavigationController"
        self.drawerController = DrawerController(centerViewController: navigationController, leftDrawerViewController: leftSideNavController, rightDrawerViewController: nil)
        self.drawerController.openDrawerGestureModeMask = .all
        self.drawerController.closeDrawerGestureModeMask = .all
        self.window = UIWindow(frame: UIScreen.main.bounds)
        self.window?.rootViewController = self.drawerController
        return true
    }