AppDelegate解耦

作为iOS整个项目的核心App delegate,随着项目的逐渐变大,会变得越来越臃肿,一不小心代码就过了千行.

大型项目的App delegate体积会大到什么程度呢?我们可以参考下国外2亿多月活的Telegram的 App delegate.是不是吓一跳,4千多行.看到这样的代码是不是很想点击左上角的x.

是时候该给App delegate解耦了,目标: 每个功能的配置或者初始化都分开,各自做各自的事情.App delegate要做到只需要调用就好了.

1.命令模式

命令模式: 发送方发送请求,然后接收方接受请求后执行,但发送方可能并不知道接受方是谁,执行的是什么操作,这样做的好处是发送方和接受方完全的松耦合,大大提高程序的灵活性.

  1. 定义好协议,把相关初始化配置代码分类
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protocol Command {
func execute()
}

struct InitializeThirdPartiesCommand: Command {
func execute() {
// 第三方库初始化代码
}
}

struct InitialViewControllerCommand: Command {
let keyWindow: UIWindow
func execute() {
// 根控制器设置代码
}
}

struct InitializeAppearanceCommand: Command {
func execute() {
// 全局外观样式配置
}
}

struct RegisterToRemoteNotificationsCommand: Command {
func execute() {
// 远程推送配置
}
}

  1. 管理者
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final class StartupCommandsBuilder {
private var window: UIWindow!

func setKeyWindow(_ window: UIWindow) -> StartupCommandsBuilder {
self.window = window
return self
}

func build() -> [Command] {
return [
InitializeThirdPartiesCommand(),
InitialViewControllerCommand(keyWindow: window),
InitializeAppearanceCommand(),
RegisterToRemoteNotificationsCommand()
]
}
}

  1. App delegate调用
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    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    StartupCommandsBuilder()
    .setKeyWindow(window!)
    .build()
    .forEach { $0.execute() }

    return true
    }

使用命令模式的好处是,如果要添加新的配置,设置完后只要加在StartupCommandsBuilder中就可以了.App delegate中不需要添加任何内容.

但这样做只能将didFinishLaunchingWithOptions中的代码解耦,App delegate中的其他方法怎样解耦呢?


2.组合模式

组合模式: 可以将对象组合成树形结构来表现”整体/部分”层次结构. 组合后可以以一致的方法处理个别对象以及组合对象.

这边我们给App delegate每个功能模块都设置一个子类,每个子类包含所有App delegate的方法.

  1. 每个子模块实现各自的功能
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    // 推送
    class PushNotificationsAppDelegate: AppDelegateType {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    print("推送配置")
    return true
    }

    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
    print("推送相关代码...")
    }

    // 其余方法
    }

    // 外观样式
    class AppearanceAppDelegate: AppDelegateType {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    print("外观样式配置")
    return true
    }
    }


    // 控制器处理
    class ViewControllerAppDelegate: AppDelegateType {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    print("根控制器设置代码")
    return true
    }
    }


    // 第三方库
    class ThirdPartiesConfiguratorAppDelegate: AppDelegateType {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    print("第三方库初始化代码")
    return true
    }

    func applicationDidEnterBackground(_ application: UIApplication) {
    print("ThirdPartiesConfiguratorAppDelegate - applicationDidEnterBackground")
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
    print("ThirdPartiesConfiguratorAppDelegate - applicationDidBecomeActive")
    }

    }

  1. 管理者
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typealias AppDelegateType = UIResponder & UIApplicationDelegate

class CompositeAppDelegate: AppDelegateType {
private let appDelegates: [AppDelegateType]

init(appDelegates: [AppDelegateType]) {
self.appDelegates = appDelegates
}

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
appDelegates.forEach { _ = $0.application?(application, didFinishLaunchingWithOptions: launchOptions) }
return true
}

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
appDelegates.forEach { _ = $0.application?(application, didRegisterForRemoteNotificationsWithDeviceToken: deviceToken) }
}


func applicationDidEnterBackground(_ application: UIApplication) {
appDelegates.forEach { _ = $0.applicationDidEnterBackground?(application)
}
}

func applicationDidBecomeActive(_ application: UIApplication) {
appDelegates.forEach { _ = $0.applicationDidBecomeActive?(application)
}
}
}

  1. App delegate调用
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@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?
let appDelegate = AppDelegateFactory.makeDefault()

enum AppDelegateFactory {
static func makeDefault() -> AppDelegateType {

return CompositeAppDelegate(appDelegates: [
PushNotificationsAppDelegate(),
AppearanceAppDelegate(),
ThirdPartiesConfiguratorAppDelegate(),
ViewControllerAppDelegate(),
]
)
}
}

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
_ = appDelegate.application?(application, didFinishLaunchingWithOptions: launchOptions)
return true
}

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
appDelegate.application?(application, didRegisterForRemoteNotificationsWithDeviceToken: deviceToken)
}

func applicationDidBecomeActive(_ application: UIApplication) {
appDelegate.applicationDidBecomeActive?(application)
}

func applicationDidEnterBackground(_ application: UIApplication) {
appDelegate.applicationDidEnterBackground?(application)
}
}

App delegate解耦相比命令模式,使用组合模式可自定义程度会更高一点.