Coordinator Pattern with Storyboards

Storyboard+.swift

import UIKit

protocol StoryboardInstantiable: NSObjectProtocol {
  associatedtype MyType
  static var defaultFileName: String { get }
  static func instantiateViewController(_ bundle: Bundle?) -> MyType
}

extension StoryboardInstantiable where Self: UIViewController {
  static var defaultFileName: String {
    return NSStringFromClass(Self.self).components(separatedBy: ".").last!
  }

  static func instantiateViewController(_ bundle: Bundle? = nil) -> Self {
    let fileName = defaultFileName
    let sb = UIStoryboard(name: fileName, bundle: bundle)
    return sb.instantiateInitialViewController() as! Self
  }
}