iOS应用的几个阶段

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{

returnYES;

}//程序启动进入执行的操作--初始化SDK,确定根视图操作等

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

}//应用失去焦点执行的操作

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

}//应用程序进入后台执行的操作----记录后台所处的页面

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

}//程序进入前台执行的操作----记录页面验证手势密码和指纹密码在应用窗口弹出，消失处理等问题

- (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.

}//程序已经处于焦点执行的操作

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

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

}//程序被终止进行的操作

这个可以类比视图的生命周期进行，在确定的时间段进行处理  从视图启动到视图销毁过程对比理解，执行相应的操作。