Refactoring Massive App Delegate

3 minute read Published: 2021-02-01

Refactoring Massive App Delegate

실제 production app 을 개발하다 보면 AppDelegate 클래스가 쉽게 비대해지고 파일수가 어마어마하게 늘어나는 경우가 비일비재하다. 이를 refactoring 하는 방법

Mediator Design Pattern

refactoring-massive-app-delegate 에 보면 다양한 디자인 패턴으로 appDelegate를 refactoring 하는 법이 나와있다 그중 mediator design pattern 으로 실제 활용한 예

AppLifecycle Mediator

먼저 AppLifeCycle mediator 를 정의한다.
아래 소스는 appDelegate.m 이 objective-c 로 구현되어 있기에 NSObject를 상속받고 objc propertyObserver를 붙였다.

import Foundation

// MARK: - AppLifecycleListener
protocol AppLifecycleListener {
  func onAppWillEnterForeground()
  func onAppDidEnterBackground()
  func onAppDidFinishLaunching()
}

extension AppLifecycleListener {
  func onAppWillEnterForeground() {}
  func onAppDidEnterBackground() {}
}

// MARK: - Mediator
@objc
class AppLifecycleMediator: NSObject {
  private let listeners: [AppLifecycleListener]
  
  init(listeners: [AppLifecycleListener]) {
    self.listeners = listeners
    super.init()
    subscribe()
  }
  
  deinit {
    NotificationCenter.default.removeObserver(self)
  }
  
  private func subscribe() {
    NotificationCenter.default.addObserver(self, selector: #selector(onAppWillEnterForeground), name: UIApplication.willEnterForegroundNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(onAppDidEnterBackground), name: UIApplication.didEnterBackgroundNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(onAppDidFinishLaunching), name: UIApplication.didFinishLaunchingNotification, object: nil)
  }
  
  @objc private func onAppWillEnterForeground() {
    listeners.forEach { $0.onAppWillEnterForeground() }
  }
  
  @objc private func onAppDidEnterBackground() {
    listeners.forEach { $0.onAppDidEnterBackground() }
  }
  
  @objc private func onAppDidFinishLaunching() {
    listeners.forEach { $0.onAppDidFinishLaunching() }
  }
}

AppListener class 구현

이제 AppLifecycleListener 를 상속하여 클래스를 구현한다.
appDelegate 에서 구현된 각각의 서비스 구현들을 여기에 Extract 하여 구현
예를 들면 기존에 AppDelegate에서 구현되어있던 location permission 관련 feature 들은 아래와 같이 AppLocationListener 구현한다.

import Foundation
import CoreLocation
import LoggingKit

class AppLocationListener: NSObject, AppLifecycleListener {
 let locationManager = CLLocationManager()
 
 fileprivate func permissionState(_ status: CLAuthorizationStatus) {
   LogService.shared.debug("LocationPermission: \(status.rawValue)", logCategory: \.debug)
   switch status {
   case .authorizedAlways, .authorizedWhenInUse:
     locationManager.startUpdatingLocation()
   case .restricted, .notDetermined:
     locationManager.requestWhenInUseAuthorization()
   case .denied:
     stopLocation()
   @unknown default:
     print("GPS: Default")
   }
 }
 
 func stopLocation() {
   locationManager.stopUpdatingHeading()
   locationManager.stopUpdatingLocation()
   locationManager.delegate = nil
 }
 
 func onAppDidFinishLaunching() {
   locationManager.delegate = self
   locationManager.desiredAccuracy = kCLLocationAccuracyBest
   let status: CLAuthorizationStatus
   if #available(iOS 14.0, *) {
     status = locationManager.authorizationStatus
   } else {
     status = CLLocationManager.authorizationStatus()
   }
   permissionState(status)
 }
}

extension AppLocationListener: CLLocationManagerDelegate {
 func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
   self.permissionState(status)
 }
 
 func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
   locationManager.stopUpdatingLocation()
 }
 
 func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
   let newLocation = locations[0]
   let geocoder = CLGeocoder()
   geocoder.reverseGeocodeLocation(newLocation) { (playmarks, error) in
     if let _ = error {
       self.stopLocation()
       return
     }
     
     if let city = playmarks?.first?.locality {
       cityDefault.saveLocationLng("\(newLocation.coordinate.longitude)")
       cityDefault.saveLocationLat("\(newLocation.coordinate.latitude)")
       cityDefault.saveLocationCity(city)
     }
   }
   stopLocation()
 }
}

그리고 AppLifecycleMediator 에 listener 에 추가

extension AppLifecycleMediator {
  @objc
  static func makeDefaultMediator() -> AppLifecycleMediator {
    let locationListener = AppLocationListener()
    let debugListener = AppDebugListener()

    return AppLifecycleMediator(listeners: [debugListener, locationListener])
  }
}

3rdParty service 들, debug feature 등 listener 로 추가하여 refactoring 해주면 된다.

add mediator to AppDelegate

이제 mediator class 를 AppDelegate 에 등록한다.
다음 코드 한줄만 appDelegate 에 추가하면 된다.

@UIApplicationMain

class AppDelegate: UIResponder, UIApplicationDelegate {

   var window: UIWindow?

   let mediator = AppLifecycleMediator.makeDefaultMediator() // 여기에 추가

   func application(_ application: UIApplication,                                           didFinishLaunchingWithOptions launchOptions:                              [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

      return true

   }
}

objective-c 구현에 붙인다면 조금 애매한데 willFinishLaunchingWithOptions 메소드에 다음과 같이 추가하였다.

@interface AppDelegate ()<CLLocationManagerDelegate, UNUserNotificationCenterDelegate, FIRMessagingDelegate, AppsFlyerLibDelegate>
{
  AppLifecycleMediator *_mediator; // 여기에 선언하고 
}


...
- (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  _mediator = [AppLifecycleMediator makeDefaultMediator]; // 구현추가.
  return YES;
}

Refactoring Massive App Delegate

Mediator Design Pattern

AppLifecycle Mediator

AppListener class 구현

add mediator to AppDelegate

Reference