AppDelegate中方法的作用

/**
*  app加载完毕的时候调用(一般只调用一次)
*
*/
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    NSLog(@"didFinishLaunchingWithOptions");
    return YES;
}

/**
*  app失去焦点的时候调用(UI控件不能正常使用)
*/
- (void)applicationWillResignActive:(UIApplication *)application
{
    NSLog(@"applicationWillResignActive");
}

/**
*  app进入后台的时候调用(app消失不见)
*/
- (void)applicationDidEnterBackground:(UIApplication *)application
{
    NSLog(@"applicationDidEnterBackground");
}

/**
*  app进入前台的时候调用(app显示出来)
*/
- (void)applicationWillEnterForeground:(UIApplication *)application
{
    NSLog(@"applicationWillEnterForeground");
}

/**
*  当app获得焦点的时候调用(这时候整个app的UI控件都能正常使用)
*/
- (void)applicationDidBecomeActive:(UIApplication *)application
{
//    UITabBarController *tabbarVc = (UITabBarController *)self.window.rootViewController;
//    NSLog(@"%@", NSStringFromCGRect(tabbarVc.tabBar.frame));
   
//    for (UIView *child in tabbarVc.tabBar.subviews) {
//        if ([child isKindOfClass:[UIImageView class]]) {
//            [child removeFromSuperview];
//        }
//    }
    NSLog(@"applicationDidBecomeActive");
}

//app进入后台:休眠,  不能接受事情(比如关闭)
/**
*  app关闭的时候调用(一般情况下不会调用)
*/
- (void)applicationWillTerminate:(UIApplication *)application
{
    NSLog(@"applicationWillTerminate");
}