我有一个视图控制器,其中我的值为 0(标签),当我从另一个视图控制器打开该视图控制器时,ViewController我已将viewDidAppear标签上的值设置为 20。它工作正常,但是当我关闭我的应用程序并再次打开我的应用程序但值没有改变viewDidLoad,因为没有任何viewDidAppear东西viewWillAppear被调用。打开我的应用程序时如何拨打电话。我必须做任何事情applicationDidBecomeActive吗?
ViewController
viewDidAppear
viewDidLoad
viewWillAppear
applicationDidBecomeActive
对事件的确切顺序感到好奇,我按如下方式检测了一个应用程序:(@Zohaib,您可以使用下面的 NSNotificationCenter 代码来回答您的问题)。
// AppDelegate.m - (void)applicationWillEnterForeground:(UIApplication *)application { NSLog(@"app will enter foreground"); } - (void)applicationDidBecomeActive:(UIApplication *)application { NSLog(@"app did become active"); } // ViewController.m - (void)viewDidLoad { [super viewDidLoad]; NSLog(@"view did load"); [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appDidBecomeActive:) name:UIApplicationDidBecomeActiveNotification object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appWillEnterForeground:) name:UIApplicationWillEnterForegroundNotification object:nil]; } - (void)appDidBecomeActive:(NSNotification *)notification { NSLog(@"did become active notification"); } - (void)appWillEnterForeground:(NSNotification *)notification { NSLog(@"will enter foreground notification"); } - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; NSLog(@"view will appear"); } - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; NSLog(@"view did appear"); }
启动时,输出如下所示:
2013-04-07 09:31:06.505 myapp[15459:11303] view did load 2013-04-07 09:31:06.507 myapp[15459:11303] view will appear 2013-04-07 09:31:06.511 myapp[15459:11303] app did become active 2013-04-07 09:31:06.512 myapp[15459:11303] did become active notification 2013-04-07 09:31:06.517 myapp[15459:11303] view did appear
进入后台,然后重新进入前台:
2013-04-07 09:32:05.923 myapp[15459:11303] app will enter foreground 2013-04-07 09:32:05.924 myapp[15459:11303] will enter foreground notification 2013-04-07 09:32:05.925 myapp[15459:11303] app did become active 2013-04-07 09:32:05.926 myapp[15459:11303] did become active notification