Programmatically change rootViewController of storyBoard

Question

I have created my project using Storyboards. The root ViewController lies inside a Storyboard, I have not written a single code in the appDelegate.

Now I want to show a tour of my app, so I want to change the root ViewController from Tab Bar to my TourVC and when the tour of the app is finished , I want to again switch back my root ViewController to Tab Bar.

So I looked up online and followed the following points

1) Remove Storyboards from app.plist file, 2) Uncheck option "isInitialViewController" from Storyboards which is checked in case of Tab Bar controller because its a root ViewController, 3) Add this code in appDelegate.m file.

self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
ProductTourViewController *PT = [[ProductTourViewController alloc] initWithNibName:@"ProductTourViewController" bundle:nil];
self.window.rootViewController = PT;
[self.window makeKeyAndVisible];
return YES;

But my app crashes with this error log,

[ProductTourViewController selectedViewController]: unrecognized selector sent to instance 0x1766a9e0

And also I get a warning,

Unsupported Configuration: Scene is unreachable due to lack of entry points and does not have an identifier for runtime access via -instantiateViewControllerWithIdentifier:.

Answer 1

Objective-C:

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
UITabBarController *rootViewController = [storyboard instantiateViewControllerWithIdentifier:@"tabBarcontroller"];
[[UIApplication sharedApplication].keyWindow setRootViewController:rootViewController];

Swift :

 let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
 let viewController = mainStoryboard.instantiateViewControllerWithIdentifier("tabBarcontroller") as UITabBarController  
   UIApplication.sharedApplication().keyWindow?.rootViewController = viewController;

Swift 3:

let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let viewController = mainStoryboard.instantiateViewController(withIdentifier: "tabBarcontroller") as! UITabBarController
UIApplication.shared.keyWindow?.rootViewController = viewController

Swift 5:

let viewController = mainStoryboard.instantiateViewController(withIdentifier: "tabBarcontroller") as! UITabBarController
UIApplication.shared.windows.first?.rootViewController = viewController
UIApplication.shared.windows.first?.makeKeyAndVisible()

Or simply like this:

let viewController = mainStoryboard.instantiateViewController(withIdentifier: "tabBarcontroller") as! UITabBarController
self.view.window?.rootViewController = viewController
self.view.window?.makeKeyAndVisible()

Both works fine!