画面遷移のProtocol(たぶんあまりよくない例)

Routable.swift

import UIKit

enum PresentDestination {
    case viewControllerA
    case viewControllerB(content: Content)

    var viewController: UIViewController {
        switch self {
        case .viewControllerA:
            return ViewControllerA.initiateWithNavigation()
        case .viewControllerB(let content):
            return ViewControllerB.initiateWithNavigation(content: content)
        }
    }

}

enum PushDestination {
    case viewControllerC
    case viewControllerD(identifier: String)

    var viewController: UIViewController {
        switch self {
        case .viewControllerC:
            return ViewControllerC.initiate()
        case .viewControllerD(let identifier):
            return ViewControllerD.initiate(identifier: identifier)
        }
    }
}

protocol Routable {
    func present(_ destination: PresentDestination, from viewController: UIViewController, animated: Bool, completion: (() -> Void)?)
    func navigationControllerPush(_ destination: PushDestination, from viewController: UIViewController, animated: Bool)
}

extension Routable {
    func present(_ destination: PresentDestination, from viewController: UIViewController, animated: Bool, completion: (() -> Void)? = nil) {
        viewController.present(destination.viewController, animated: animated, completion: completion)
    }

    func navigationControllerPush(_ destination: PushDestination, from viewController: UIViewController, animated: Bool) {
        viewController.navigationController?.pushViewController(destination.viewController, animated: true)
    }
}


////
使用時
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1. 画面遷移処理を書きたいViewControllerやPresenterにRoutableプロトコル適用
2. 画面遷移したい箇所で、

// ViewControllerの時
func showViewControllerA() {
    present(.viewControllerA, from: self, animated: true)
}

func pushViewControllerD() {
    navigationControllerPush(.viewControllerD(identifier: "fugaId"), from: self, animated: true)
}

// Presenterの時
func showViewControllerA() {
    guard let vc = view as? HogeViewController else {
        return
    }
    present(.viewControllerA, from: vc, animated: true)
}

func pushViewControllerD() {
    guard let vc = view as? HogeViewController else {
        return
    }
    navigationControllerPush(.viewControllerD(identifier: "fugaId"), from: vc, animated: true)
}