UIWindow UIScreen UIViewController UIView之间的关系

转自：

http://blog.csdn.net/heng615975867/article/details/39053695

UIScreen(屏幕，一直存在)
---》UIWindow(画框)
---》UIViewController(视图控制器)
---》UIView(视图)

//didFinishLaunchingWithOptions 方法：顾名思义。在app开始运行时会调用里面的方法。

-(BOOL)application:(UIApplication *)applicationdidFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    //返回的是带有状态栏的矩形
    self.window = [[[UIWindow alloc]initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

   //返回的是带有状态栏的Rect 
  CGRect bound = [[UIScreen mainScreen]bounds]; 
    NSLog(@"boundwith:%f    boundheight:%f",bound.size.width,bound.size.height); 
  NSLog(@"boundx:%f    boundy:%f",bound.origin.x,bound.origin.y); 
    //2012-08-0323:21:45.716 DinkMixer[599:c07]boundwith:320.000000    boundheight:480.000000
    //2012-08-03 23:21:45.719 DinkMixer[599:c07] boundx:0.000000    boundy:0.000000

    CGRect appBound = [[UIScreenmainScreen]applicationFrame];  //返回的是不带有状态栏的Rect
    NSLog(@"appBoundwith:%f    boundheight:%f",appBound.size.width,appBound.size.height); 
  NSLog(@"appBoundx:%f    boundy:%f",appBound.origin.x,appBound.origin.y);
    //2012-08-0323:21:45.720 DinkMixer[599:c07]appBoundwith:320.000000    boundheight:460.000000
  //2012-08-03 23:21:45.720 DinkMixer[599:c07]appBoundx:0.000000    boundy:20.000000
    //很明显状态栏占用了空间20像素

    //根据nib文件的名称来创建一个视图控制器
    MasterViewController*masterViewController = [[[MasterViewController alloc]initWithNibName:@"MasterViewController" bundle:nil] autorelease];

   //创建一个导航控制器，并指定该导航控制器的根视图控制器为上面建立的masterViewController
    self.navigationController= [[[UINavigationController alloc]initWithRootViewController:masterViewController] autorelease];
  //窗体（window）有一个根视图控制器——这个视图控制器负责配置当窗体显示时最先显示的视图。要让你的视图控制器的内容显示在窗体中，需要去设置窗体的根视图控制器为你的视图控制器。
    self.window.rootViewController = self.navigationController;
   

    //这行代码会让包含了视图控制器视图的Window窗口显示在屏幕上。
    [self.window makeKeyAndVisible];
    return YES;
}

---》UIView(视图)(视图)