UIApplication of Multi-controller

UIApplication Introduction

• UIApplication objects are symbols of the application
• Each application has its own UIApplication object, which is a singleton object that can be [UIApplication sharedApplication] obtained and cannot be created with Alloc
• The first object created after a program is started is a UIApplication object
• With this object, you can do an application-level operation:
  • Displays the red reminder number in the upper-right corner of the program icon (iOS8 to register for notification):applicationIconBadgeNumber(属性)
  • Display the visibility of the networking indicator (IOS7 to controller management, so set): statusBarHidden(属性)
  • Call:openURL(方法)
  • Texting:openURL(方法)
  • Browse the Web:openURL(方法)
  • Wait a minute
• Note: The Load class method (Cannot access property): Called when the class is loaded into memory, it is earlier than the Main method call

Agent Delegate

• The app is disturbed to produce a series of trivia, when UIApplication notifies its proxy object to handle

• Handling Events:

  // 应用程序启动完成的时候调用- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {return YES;}// 当应用程序即将失去焦点(不可与用户交互)- (void)applicationWillResignActive:(UIApplication *)application {}// 应用程序进入后台- (void)applicationDidEnterBackground:(UIApplication *)application {}// 应用程序将要进入前台- (void)applicationWillEnterForeground:(UIApplication *)application {}// 应用程序完全获得焦点(可与用户交互)- (void)applicationDidBecomeActive:(UIApplication *)application {}// 程序即将关闭的时候- (void)applicationWillTerminate:(UIApplication *)application {}

How the application starts

int main(int argc, char * argv[]) {    @autoreleasepool {        // 第三个参数:设置UIApplication的对象的名称,只能它或者它子类,nil == @"UIApplication"        // 第四个参数:创建代理对象,遵守了UIApplicationDelegate协议,把这个对象设为应用程序(UIApplication)的代理        //           用NSStringFromClass:将一个类名转换成字符串---1.提示功能 2.避免输入错误        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));    }}

// 程序的启动原理// 1.执行main -> UIApplicationMain// 2.创建UIApplication对象,并设置它的代理// 3.开启了一个事件循环(主运行循环)(死循环) -> 保证应用程序能一直运行// 4.应用程序加载Info.plist配置文件,判断该文件中是否有main值,如果有就会去加载Main.storyBoard,     如果没有就执行didFinishLaunchingWithOptions:方法,应用程序启动完毕

UIApplication of Multi-controller