iOS_程序执行顺序

关于这个话题其实可以变化的不多, 毕竟执行顺序是死的, 只是这个问题在面试中会被问到, 所以拿出来说一下

1.main.m 程序的入口

这里 main 函数为我们做了三件事情

a.创建了一个 UIApplication 对象;

b.指定了一个 UIApplication 的代理委托;

c.UIApplicationMain 会为我们开启个事件循环(控制我们手指触到屏幕或者其他的事件);

int main(int argc,char * argv[]) {

    @autoreleasepool {

        returnUIApplicationMain(argc, argv, nil,NSStringFromClass([AppDelegateclass]));

    }

}

2.xxx - Prefix.pch预编译头文件

3.xxx - Info.plist程序配置文件

4.InfoPlist.string 国际化文件

5.MyProject.app 最终程序

6.framework 是程序用到的框架

UIApplicationDelegate

/*UIApplicationDelegate是个协议,定义了一堆监测程序执行的方法.这些方法都有自己的触发事件;

      大致分为几类:程序启动、活跃/非活跃状态、前/后台切换、推送通知、内存警告等;*/

其中appDelegate中, 在程序还会涉及到下面这些方法,分别是在程序进行至各个状态时调用的

#pragma mark -应用程序将要取消活动状态;

- (void)applicationWillResignActive:(UIApplication *)application {

    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.

    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.

}

#pragma mark -应用程序将要进入后台;

- (void)applicationDidEnterBackground:(UIApplication *)application {

    // 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.

}

#pragma mark -应用程序将要进入前台;

- (void)applicationWillEnterForeground:(UIApplication *)application {

    // 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.

}

#pragma mark -应用程序变为活动状态;

- (void)applicationDidBecomeActive:(UIApplication *)application {

    // 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.

}

#pragma mark -应用程序将要终止(通常用在后台下载至一半是退出程序时);

- (void)applicationWillTerminate:(UIApplication *)application {

    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.

}