有没有觉得你的AppDelegate杂乱无章？代码几百行上千行？集成了无数的功能，如推送、埋点、日志统计、Crash统计等等，感觉AppDelegate无所不能。

来一段一般的AppDelegate代码，来自网上一篇文章：

@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}}
}
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看完后，有没有一个类就能完成整个应用的想法？今天，我们的目的就是使得AppDelegate这个类代码极限缩减。

如果大家有了解过微服务的话，大家就会知道，一个服务专职做一件事情，然后由网关来调度，这样的逻辑是非常清晰的，也非常便于维护，我们这次的改造也是源于这样的思路的。

按照上图，以后我们的AppDelegate只做网关对应的功能，其他具体业务，交由不同的服务去做，那么，我们应该如何实现这样的想法呢？

1.首先我们创建一个文件TDWApplicationDelegate.swift 里面的代码：

/// UIApplicationDelegate 协议扩展
public protocol TDWApplicationDelegate: UIApplicationDelegate {}
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这里定义了一个***TDWApplicationDelegate***，继承***UIApplicationDelegate***。这个协议是方便以后扩展用的。

2.我们再创建一个文件TDWAppDelegateService.swift 代码为：

import Foundationopen class TDWAppDelegateService: UIResponder, TDWApplicationDelegate {/// 启动服务的数组open var __services:[TDWApplicationDelegate] = []
}// MARK: - 启动
extension TDWAppDelegateService {open func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {__services.forEach {_ = $0.application?(application, didFinishLaunchingWithOptions: launchOptions)}return true}
}// MARK: - 其他应用唤起
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: - 前后台
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: - 推送相关
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相关
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) }}
}
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这个是本文的核心类，他主要做了些什么事情呢？

1.定义了一个服务数组，把服务都统一管理。 2.在extension里面实现常用的AppDelegate生命周期的协议。因为***__services***里面的服务都是继承于***TDWApplicationDelegate***，所以，没有服务，其实能实现AppDelegate生命周期。所以，在这个***TDWAppDelegateService***上，我在他所有的生命周期里同步遍历调用所有服务***__services***的对等生命周期，这样，就变相于我收到系统的信息后，会同步给各个服务，让他们自己处理了。

这样，我们就完成了整个服务的框架了。那么，我们如何使用呢？ 这里，我以2个服务作为例子，当然，你可以构建10个，只要你喜欢。

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}
}
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这里有2个服务，一个是初始化服务，一个是日志服务，他们都只做一件事件，打印相关的字符串。

ok，下面我们构建下我们的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)}}
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AppDelegate非常简洁，他只有短短几句代码。 1.首先AppDelegate继承于***TDWAppDelegateService*** 2.然后重载***didFinishLaunchingWithOptions***方法，把服务实例放到***__services***数组就可以了。 3.最后，你就可以运行看结果了。

没错，服务按顺序执行对应的功能，也就是打印对应的字符串。

好了，以上就是本文要介绍的内容，欢迎评论反馈，谢谢！！