Swift 3, Xcode 8 Instantiate View Controller is not working

Question

Xcode 8 when it compiles says to change instantiate viewcontroller with identifier to simply, instantiate view controller. I did that, why does it give two errors?

I'm working with Swift 3. I want to change pages programmatically.I've read a lot of other questions on the topic. All of them use instantiate view controller with the identifier. They haven't adopted the new language.

@IBAction func switchPage(_ sender: UIButton) {

    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let viewController = 
storyboard.instantiateViewController("secondViewController") as! 
UIViewController
    self.presentViewController(secondViewController, animated: true, 
completion: nil)    

}

Thanks. I changed the code as suggested, and receive only one error: Value of optional type 'UIStoryboard?' not unwrapped; did you mean to use '!' or '?'? Should I add an exclamation point somewhere?

import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a 
nib.
}

@IBAction func ch(_ sender: UIButton) {



    let viewController = 
storyboard.instantiateViewController(withIdentifier: 
"secondViewController") as! UIViewController
    self.present(viewController, animated: true)



}




override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}



}

Answer 1

Try like this.

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let viewController = storyboard.instantiateViewController(withIdentifier :"secondViewController") as! UIViewController
self.present(viewController, animated: true)    

Answer 2

It's worked for me:

 let gameScene = UIStoryboard(name: "Main", bundle:nil).instantiateViewController(withIdentifier: "ViewController") as UIViewController
        let appDelegate = (UIApplication.shared.delegate as! AppDelegate)
        appDelegate.window?.rootViewController = gameScene

Answer 3

It's worked for me by this:

let vc = UIStoryboard(name: "ZWLStaticTabVc", bundle: nil).instantiateInitialViewController()
self.navigationController?.pushViewController(vc!, animated: true)