instantiate viewcontroller using identifier.

Instantiatable.swift

protocol Instantiatable {
    static var storyboard: Storyboard { get }
    static func instantiate() -> Self
}

extension Instantiatable where Self: UIViewController {
    static func instantiate() -> Self {
        // swiftlint:disable force_cast
        UIStoryboard(storyboard).instantiateViewController(withIdentifier: String(describing: Self.self)) as! Self
    }
}

Storyboard.swift

enum Storyboard: String {
    case main = "Main"
}

extension UIStoryboard {
    convenience init(_ storyboard: Storyboard) {
        self.init(name: storyboard.rawValue, bundle: nil)
    }
}

extension UIViewController {
    static func instantiate(storyboard: Storyboard) -> Self {
        // swiftlint:disable force_cast
        UIStoryboard(storyboard).instantiateViewController(withIdentifier: String(describing: Self.self)) as! Self
    }
}

ViewController.swift

// Usage:

class ViewController: UIViewController, Instantiatable {
    static let storyboard: Storyboard = .main
}