WindowLevel是UIWindow的一个属性。系统定义的一共有3种。
UIKIT_EXTERN const UIWindowLevel UIWindowLevelNormal;
UIKIT_EXTERN const UIWindowLevel UIWindowLevelAlert;
UIKIT_EXTERN const UIWindowLevel UIWindowLevelStatusBar;
代码：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
NSLog(@"UIWindowLevelNormal=%f UIWindowLeveStatusBar=%f UIWindowLevelAlert=%f",UIWindowLevelNormal,UIWindowLevelStatusBar,UIWindowLevelAlert);
return YES;
}
输出结果：
2015-07-19 21:02:45.448 WindowLevelDemo[775:24283] UIWindowLevelNormal=0.000000 UIWindowLeveStatusBar=1000.000000 UIWindowLevelAlert=2000.000000
参考资料：《iOS开发进阶》-唐巧