ios—iPhone开发之生命周期

[来源] 达内    [编辑] 达内   [时间]2012-09-13

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

  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 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AppD elegate.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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