iOS学习笔记（二.iOS程序执行流程）

一个ios程序在启动的时候系统会自动读取该程序的配置文件

info.plist

之后它在读取到文件中的

main storyboard file base name

改变量的值指明程序启动哪个storyboard，每一个storyboard文件和一个ViewController.swift文件相对应
在一个ViewController.swift文件中，有一重载的方法

    override func viewDidLoad() {        super.viewDidLoad()        // Do any additional setup after loading the view, typically from a nib.    }

在storyboard对应的ViewController.swift文件被成功加载后会被调用

AppDelegate.swift   //该文件用来侦听应用程序相关状态

其中的方法

    func applicationDidEnterBackground(application: UIApplication) {        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.    }

当应用程序完全进入后台会被调用

    func applicationWillEnterForeground(application: UIApplication) {        // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.    }

在应用程序即将进入前端时呈现

    func applicationDidBecomeActive(application: UIApplication) {        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.    }

在应用程序处于焦点时被激活