有沒有覺得你的AppDelegate雜亂無章？代碼幾百行上千行？集成了無數的功能，如推送、埋點、日志統計、Crash統計等等，感覺AppDelegate無所不能。

來一段一般的AppDelegate代碼，來自網上一篇文章：

@UIApplicationMain class AppDelegate: UIResponder, UIApplicationDelegate {var window: UIWindow?func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {Log(info: "AppDelegate.didFinishLaunchingSite started.")application.setMinimumBackgroundFetchInterval(UIApplicationBackgroundFetchIntervalMinimum)UNUserNotificationCenter.current().register(delegate: self,actions: [UNNotificationAction(identifier: "favorite", title: .localized(.favorite))])// Initialize Google Analyticsif !AppGlobal.userDefaults[.googleAnalyticsID].isEmpty {GAI.sharedInstance().tracker(withTrackingId: AppGlobal.userDefaults[.googleAnalyticsID])}// Declare data format from remote REST APIJSON.dateFormatter.dateFormat = ZamzamConstants.DateTime.JSON_FORMAT// Initialize componentsAppLogger.shared.setUp()AppData.shared.setUp()// Select home tab(window?.rootViewController as? UITabBarController)?.selectedIndex = 2setupTheme()Log(info: "App finished launching.")// Handle shortcut launchif let shortcutItem = launchOptions?[.shortcutItem] as? UIApplicationShortcutItem {performActionForShortcutItem(application, shortcutItem: shortcutItem)return false}return true}func application(_ application: UIApplication, continue userActivity: NSUserActivity, restorationHandler: @escaping ([Any]?) -> Void) -> Bool {guard userActivity.activityType == NSUserActivityTypeBrowsingWeb, let webpageURL = userActivity.webpageURL else { return false }Log(info: "AppDelegate.continueUserActivity for URL: \(webpageURL.absoluteString).")return navigateByURL(webpageURL)}func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {Log(info: "AppDelegate.performFetch started.")scheduleUserNotifications(completionHandler: completionHandler)}func application(_ application: UIApplication, performActionFor shortcutItem: UIApplicationShortcutItem, completionHandler: @escaping (Bool) -> Void) {window?.rootViewController?.dismiss(animated: false, completion: nil)guard let tabController = window?.rootViewController as? UITabBarController else { completionHandler?(false); return }switch shortcutItem.type {case "favorites":tabController.selectedIndex = 0case "search":tabController.selectedIndex = 3case "contact":guard let url = URL(string: "mailto:\(AppGlobal.userDefaults[.email])") else { break }UIApplication.shared.open(url)default: break}completionHandler?(true)} }// MARK: - User Notification Delegateextension AppDelegate {func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {guard let id = response.notification.request.content.userInfo["id"] as? Int,let link = response.notification.request.content.userInfo["link"] as? String,let url = try? link.asURL()else { return }switch response.actionIdentifier {case UNNotificationDefaultActionIdentifier: _ = navigateByURL(url)case "favorite": PostService().addFavorite(id)case "share": _ = navigateByURL(url)default: break}completionHandler()}private func scheduleUserNotifications(completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {// Get latest posts from server// Persist network manager instance to ensure lifespan is not interruptedurlSessionManager = PostService().updateFromRemote {guard case .success(let results) = $0 else { return completionHandler(.failed) }guard let id = results.created.first,let post = (try? Realm())?.object(ofType: Post.self, forPrimaryKey: id)else { return completionHandler(.noData) }var attachments = [UNNotificationAttachment]()// Completion process on exitfunc deferred() {// Launch notificationUNUserNotificationCenter.current().add(body: post.previewContent,title: post.title,attachments: attachments,timeInterval: 5,userInfo: ["id": post.id,"link": post.link],completion: {guard $0 == nil else { return Log(error: "Could not schedule the notification for the post: \($0.debugDescription).") }Log(debug: "Scheduled notification for post during background fetch.")})completionHandler(.newData)}// Get remote media to attach to notificationguard let link = post.media?.thumbnailLink else { return deferred() }let thread = Thread.currentUNNotificationAttachment.download(from: link) {defer { thread.async { deferred() } }guard $0.isSuccess, let attachment = $0.value else {return Log(error: "Could not download the post thumbnail (\(link)): \($0.error.debugDescription).")}// Store attachment to schedule notification laterattachments.append(attachment)}}} }// MARK: - Internal functionsprivate extension AppDelegate {func setupTheme() {window?.tintColor = UIColor(rgb: AppGlobal.userDefaults[.tintColor])if !AppGlobal.userDefaults[.titleColor].isEmpty {UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor(rgb: AppGlobal.userDefaults[.titleColor])]}// Configure tab barif let controller = window?.rootViewController as? UITabBarController {controller.tabBar.items?.get(1)?.image = UIImage(named: "top-charts", inBundle: AppConstants.bundle)controller.tabBar.items?.get(1)?.selectedImage = UIImage(named: "top-charts-filled", inBundle: AppConstants.bundle)controller.tabBar.items?.get(2)?.image = UIImage(named: "explore", inBundle: AppConstants.bundle)controller.tabBar.items?.get(2)?.selectedImage = UIImage(named: "explore-filled", inBundle: AppConstants.bundle)if !AppGlobal.userDefaults[.tabTitleColor].isEmpty {UITabBarItem.appearance().setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor(rgb: AppGlobal.userDefaults[.tabTitleColor])], for: .selected)}}// Configure dark mode if applicableif AppGlobal.userDefaults[.darkMode] {UINavigationBar.appearance().barStyle = .blackUITabBar.appearance().barStyle = .blackUICollectionView.appearance().backgroundColor = .blackUITableView.appearance().backgroundColor = .blackUITableViewCell.appearance().backgroundColor = .clear}} } 復制代碼

看完后，有沒有一個類就能完成整個應用的想法？今天，我們的目的就是使得AppDelegate這個類代碼極限縮減。

如果大家有了解過微服務的話，大家就會知道，一個服務專職做一件事情，然后由網關來調度，這樣的邏輯是非常清晰的，也非常便于維護，我們這次的改造也是源于這樣的思路的。

按照上圖，以后我們的AppDelegate只做網關對應的功能，其他具體業務，交由不同的服務去做，那么，我們應該如何實現這樣的想法呢？

1.首先我們創建一個文件TDWApplicationDelegate.swift 里面的代碼：

/// UIApplicationDelegate 協議擴展 public protocol TDWApplicationDelegate: UIApplicationDelegate {} 復制代碼

這里定義了一個***TDWApplicationDelegate***，繼承***UIApplicationDelegate***。這個協議是方便以后擴展用的。

2.我們再創建一個文件TDWAppDelegateService.swift 代碼為：

import Foundationopen class TDWAppDelegateService: UIResponder, TDWApplicationDelegate {/// 啟動服務的數組open var __services:[TDWApplicationDelegate] = [] }// MARK: - 啟動 extension TDWAppDelegateService {open func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {__services.forEach {_ = $0.application?(application, didFinishLaunchingWithOptions: launchOptions)}return true} }// MARK: - 其他應用喚起 extension TDWAppDelegateService {// iOS 9.0 及以下open func application(_ application: UIApplication, open url: URL, sourceApplication: String?, annotation: Any) -> Bool {__services.forEach {_ = $0.application?(application, open: url, sourceApplication: sourceApplication, annotation: annotation)}return true}// iOS 9.0 以上open func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {if #available(iOS 9.0, *) {__services.forEach {_ = $0.application?(app, open: url, options: options)}return true}else {return false}} }// MARK: - 前后臺 extension TDWAppDelegateService {open func applicationWillEnterForeground(_ application: UIApplication) {__services.forEach { $0.applicationWillEnterForeground?(application) }}open func applicationDidEnterBackground(_ application: UIApplication) {__services.forEach { $0.applicationDidEnterBackground?(application) }}open func applicationDidBecomeActive(_ application: UIApplication) {__services.forEach { $0.applicationDidBecomeActive?(application) }}open func applicationWillResignActive(_ application: UIApplication) {__services.forEach { $0.applicationWillResignActive?(application) }}open func application(_ application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: @escaping () -> Void) {__services.forEach{ $0.application?(application, handleEventsForBackgroundURLSession: identifier, completionHandler: completionHandler)}} }// MARK: - 退出 extension TDWAppDelegateService {open func applicationWillTerminate(_ application: UIApplication) {__services.forEach { $0.applicationWillTerminate?(application) }}open func applicationDidReceiveMemoryWarning(_ application: UIApplication) {__services.forEach { $0.applicationDidReceiveMemoryWarning?(application) }} }// MARK: - 推送相關 extension TDWAppDelegateService {open func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {__services.forEach { $0.application?(application, didRegisterForRemoteNotificationsWithDeviceToken: deviceToken) }}open func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {__services.forEach { $0.application?(application, didFailToRegisterForRemoteNotificationsWithError: error) }}// NS_AVAILABLE_IOS(7_0);open func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {__services.forEach { $0.application?(application, didReceiveRemoteNotification: userInfo, fetchCompletionHandler: completionHandler)}} }// MARK: - 3DTouch相關 extension TDWAppDelegateService {@available(iOS 9.0, *)open func application(_ application: UIApplication, performActionFor shortcutItem: UIApplicationShortcutItem, completionHandler: @escaping (Bool) -> Void) {__services.forEach { $0.application?(application, performActionFor: shortcutItem, completionHandler: completionHandler) }} } 復制代碼

這個是本文的核心類，他主要做了些什么事情呢？

1.定義了一個服務數組，把服務都統一管理。 2.在extension里面實現常用的AppDelegate生命周期的協議。因為***__services***里面的服務都是繼承于***TDWApplicationDelegate***，所以，沒有服務，其實能實現AppDelegate生命周期。所以，在這個***TDWAppDelegateService***上，我在他所有的生命周期里同步遍歷調用所有服務***__services***的對等生命周期，這樣，就變相于我收到系統的信息后，會同步給各個服務，讓他們自己處理了。

這樣，我們就完成了整個服務的框架了。那么，我們如何使用呢？ 這里，我以2個服務作為例子，當然，你可以構建10個，只要你喜歡。

import TDWAppDelegateServiceclass TDWInitializeService: NSObject, TDWApplicationDelegate {func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {print("TDWInitializeService")return true} }class TDWLogService: NSObject, TDWApplicationDelegate {func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {print("TDWLogService")return true} } 復制代碼

這里有2個服務，一個是初始化服務，一個是日志服務，他們都只做一件事件，打印相關的字符串。

ok，下面我們構建下我們的AppDelegate：

import UIKit import TDWAppDelegateService@UIApplicationMain class AppDelegate: TDWAppDelegateService {var window: UIWindow?override func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {// Override point for customization after application launch.__services = [TDWInitializeService(), TDWLogService()]return super.application(application, didFinishLaunchingWithOptions: launchOptions)}} 復制代碼

AppDelegate非常簡潔，他只有短短幾句代碼。 1.首先AppDelegate繼承于***TDWAppDelegateService*** 2.然后重載***didFinishLaunchingWithOptions***方法，把服務實例放到***__services***數組就可以了。 3.最后，你就可以運行看結果了。

沒錯，服務按順序執行對應的功能，也就是打印對應的字符串。

好了，以上就是本文要介紹的內容，歡迎評論反饋，謝謝！！

轉載于:https://juejin.im/post/5cb97755518825328e00aac2

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