- UIView是视图的基类
- UIViewController视图控制器的基类
- UIResponder表示一个可以接受触摸屏上触摸事件的对象
- UIWin（窗口）是视图的一个子类，窗口的主要功能：1、提供一个区域来显示视图，2、将事件（event）分发给视图。
self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen] bounds]; self.window.rootViewCOntroller= self.viewController; [self.window makeKeyAndVisible];
UIScreen
- UIScreen对象可以充当iOS设备物理屏幕的替代者，通过[[UIScreen mainScreen] bounds]可以获得设备的屏幕大小
UIWindow
- 通过UIApplication获取当前keyWindow，keyWindow是用来管理键盘以及触摸类的消息，并且只能有一个window是keyWindow.
- UIWindow *keyWindow = [UIApplication sharedApplication].keyWindow;
- 每个UIWindow对象配置windowLevel属性，大部分时候不应该去改变windowL.
- UIWindow有3个级别，对应了3种显示优先级。通过windowLevel设置，优先级为：UIWindowLevel > UIWindowLevelStatusBar > UIWindowLevelNormal
//didFinishLauchingWithOptions self.windOnw= [[[UIWindow alloc] initWithFrame:[[UIScreen mainScrren] bounds]]; self.window.backgrOndColor= [UIColor whiteColor]; [self.window makeKeyAndVisible]; NSLog(@"self.window level: %@",self.windonw.level); UIButton *startButton = [UIButton buttonWithType:UIButtonTypeRounedRect]; startButton.frame = CCRectMake(320/2-120/2,180,120,35); [startButton setTile:@"警告" action:@selector(alertUser) forControlEvents:UIControlEventTouchUpInside]; [self.window addSubview:startButton]; return YES;
// alerUser -(void)alertUser { UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"提示" message:@"警告框是alert Level级别的" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil]; [alertView show]; }