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IT培训 > 资料库 > ios—iPhone开发之生命周期
  • ios—iPhone开发之生命周期

    发布:IT培训 来源:资料库 时间:2014-12-29

  • 在初次接触iPhone开发的时候,简直就是一头雾水,这是哪里跟哪里啊?本是做Android开发的我,第一次建立iPhone开发而得到初始代码,心里那纠结比我初次接触Android的情况还要糟糕!不说那么多废话了,第一编文章首先来熟悉一下iPhone程序的生命周期吧,这对整个开发周期也是非常有用的!

    iPhone app 与 Android app在生命周期在大体上是相同,但是不同的时Android的程序生命周期都体现在每个页面Activity上,也就是说,在开发Android app的时候,我们只需要管理好每个页面Activity的生命周期,app的生命周期就无需我们太操心了!而iPhone app是严格按照MVC模型开发出来的程序,“委托”这一概念是非常重要的,理所当然,iPhone app的生命周期也是在“委托”上实现的,我们在建立iPhone app的初始状态就可以看到两个文件:AppDelegate.h和AppDelegate.m!这两个文件就是我刚刚所说的“委托”的头文件和实现文件!AppDelegate.m上就可以看到app的生命周期所触发全部方法!iPhone的生命周期分为两种,一是程序的生命周期,二是视图(也就是相当于Android的Activity)的生命周期!

    首先,介绍程序的生命周期:(表述能力有待提高,上代码最实际)

    [plain]

    //首次加载,触发的方法,开始加载程序

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

    {

    NSLog(@"app didFinishLaunchingWithOptions");

    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    // Override point for customization after application launch.

    self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController" bundle:nil] autorelease];

    self.window.rootViewController = self.viewController;

    [self.window makeKeyAndVisible];

    return YES;

    }

    //当用户点击菜单健,程序放弃激活状态

    - (void)applicationWillResignActive:(UIApplication *)application

    {

    NSLog(@"applicationWillResignActive");

    }

    //进入后台,线程被挂起

    - (void)applicationDidEnterBackground:(UIApplication *)application

    {

    NSLog(@"applicationDidEnterBackground");

    }

    //程序未结束,点击程序返回前台,再次获取激活状态,触发applicationDidBecomeActive方法!

    - (void)applicationWillEnterForeground:(UIApplication *)application

    {

    NSLog(@"applicationWillEnterForeground");

    }

    //完成激活,可以与用户交互

    - (void)applicationDidBecomeActive:(UIApplication *)application

    {

    NSLog(@"applicationDidBecomeActive");

    }

    //程序结束时触发

    - (void)applicationWillTerminate:(UIApplication *)application

    {

    NSLog(@"applicationWillTerminate");

    }

    下面让我们看一下视图的生命周期:

    [plain]

    - (void)viewDidLoad

    {

    [super viewDidLoad];

    NSLog(@"viewDidLoad");

    }

    - (void)viewDidUnload

    {

    [super viewDidUnload];

    secondViewController = nil;

    NSLog(@"viewDidUnload");

    }

    -(void)viewWillAppear:(BOOL)animated

    {

    [super viewWillAppear:YES];

    NSLog(@"viewWillAppear");

    }

    -(void)viewDidAppear:(BOOL)animated

    {

    [super viewDidAppear:YES];

    NSLog(@"viewDidAppear");

    }

    -(void)viewDidDisappear:(BOOL)animated

    {

    [super viewDidDisappear:YES];

    NSLog(@"viewDidDisappear");

    }

    -(void)viewWillDisappear:(BOOL)animated

    {

    [super viewWillDisappear:YES];

    NSLog(@"viewWillDisappear");

    }

    从方法名,我们都可以看得出,视图生命周期里面大概触发的方法。

    现在我们运行一下程序,然后从第一个视图切换到第二个视图,再回到第一个视图。让我们看一下,从程序、视图的出现,消亡所触发的所有方法: www.2cto.com

    [plain]

    2012-05-10 11:29:13.426 iPhoneLifeCycle[877:f803] app didFinishLaunchingWithOptions

    2012-05-10 11:29:13.459 iPhoneLifeCycle[877:f803] viewDidLoad

    2012-05-10 11:29:13.462 iPhoneLifeCycle[877:f803] viewWillAppear

    2012-05-10 11:29:13.465 iPhoneLifeCycle[877:f803] applicationDidBecomeActive

    2012-05-10 11:29:13.472 iPhoneLifeCycle[877:f803] viewDidAppear

    2012-05-10 11:29:15.054 iPhoneLifeCycle[877:f803] viewWillDisappear

    2012-05-10 11:29:15.061 iPhoneLifeCycle[877:f803] viewDidDisappear

    2012-05-10 11:29:16.476 iPhoneLifeCycle[877:f803] viewDidLoad

    2012-05-10 11:29:16.478 iPhoneLifeCycle[877:f803] viewWillAppear

    2012-05-10 11:29:16.483 iPhoneLifeCycle[877:f803] viewDidAppear

    2012-05-10 11:29:21.790 iPhoneLifeCycle[877:f803] applicationWillResignActive

    2012-05-10 11:29:21.796 iPhoneLifeCycle[877:f803] applicationDidEnterBackground

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