Kaeru can switch ViewController in NavigationController like iOS task manager UI (after iOS 9).

You can use HistoryNavigationController, that sub class of UINavigationController. It can be used like UINavigationController.

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

    let viewContoller = UIViewController()
    let navigationController = HistoryNavigationController(rootViewController: viewContoller)

    window?.rootViewController = navigationController

    window?.makeKeyAndVisible()

    return true
}

And you can call self.navigationController?.presentHistory() in UIViewController sub class. After it, appearance would change like iOS task manager UI.

@IBAction func showViewerButtonPressed(sender: AnyObject) {
    navigationController?.presentHistory()
}

And it's possible tap each ViewController snap shots. After it, begin scale animation and called automatically UINavigationContoller.popToViewController.

When called HistoryNavigationController.presentHistory(), it's possible to set a custom backgroundView.

let view = UIView(frame: UIScreen.mainScreen().bounds)
view.backgroundColor = .redColor()
navigationController?.presentHistory(view)

This sample code write and run, when HistoryNavigationController appear, background becomes red.

• Support cocoapods.
• Support Carthage.
• Add delegate methods.
• Test.

Kaeru is available under the MIT license. See the LICENSE file for more info.