//后台通知:屏幕操作通知等等
UIKIT_EXTERN NSString *const UIApplicationDidEnterBackgroundNotification NS_AVAILABLE_IOS(4_0);
UIKIT_EXTERN NSString *const UIApplicationWillEnterForegroundNotification NS_AVAILABLE_IOS(4_0);
UIKIT_EXTERN NSString *const UIApplicationDidFinishLaunchingNotification;
UIKIT_EXTERN NSString *const UIApplicationDidBecomeActiveNotification;
UIKIT_EXTERN NSString *const UIApplicationWillResignActiveNotification;
UIKIT_EXTERN NSString *const UIApplicationDidReceiveMemoryWarningNotification;
UIKIT_EXTERN NSString *const UIApplicationWillTerminateNotification;
UIKIT_EXTERN NSString *const UIApplicationSignificantTimeChangeNotification;
UIKIT_EXTERN NSString *const UIApplicationWillChangeStatusBarOrientationNotification __TVOS_PROHIBITED; // userInfo contains NSNumber with new orientation
UIKIT_EXTERN NSString *const UIApplicationDidChangeStatusBarOrientationNotification __TVOS_PROHIBITED; // userInfo contains NSNumber with old orientation
UIKIT_EXTERN NSString *const UIApplicationStatusBarOrientationUserInfoKey __TVOS_PROHIBITED; // userInfo dictionary key for status bar orientation
UIKIT_EXTERN NSString *const UIApplicationWillChangeStatusBarFrameNotification __TVOS_PROHIBITED; // userInfo contains NSValue with new frame
UIKIT_EXTERN NSString *const UIApplicationDidChangeStatusBarFrameNotification __TVOS_PROHIBITED; // userInfo contains NSValue with old frame
UIKIT_EXTERN NSString *const UIApplicationStatusBarFrameUserInfoKey __TVOS_PROHIBITED; // userInfo dictionary key for status bar frame
UIKIT_EXTERN NSString *const UIApplicationBackgroundRefreshStatusDidChangeNotification NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsURLKey NS_AVAILABLE_IOS(3_0); // userInfo contains NSURL with launch URL
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsSourceApplicationKey NS_AVAILABLE_IOS(3_0); // userInfo contains NSString with launch app bundle ID
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsRemoteNotificationKey NS_AVAILABLE_IOS(3_0) __TVOS_PROHIBITED; // userInfo contains NSDictionary with payload
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsLocalNotificationKey NS_AVAILABLE_IOS(4_0) __TVOS_PROHIBITED; // userInfo contains a UILocalNotification
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsAnnotationKey NS_AVAILABLE_IOS(3_2); // userInfo contains object with annotation property list
UIKIT_EXTERN NSString *const UIApplicationProtectedDataWillBecomeUnavailable NS_AVAILABLE_IOS(4_0);
UIKIT_EXTERN NSString *const UIApplicationProtectedDataDidBecomeAvailable NS_AVAILABLE_IOS(4_0);
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsLocationKey NS_AVAILABLE_IOS(4_0); // app was launched in response to a CoreLocation event.
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsNewsstandDownloadsKey NS_AVAILABLE_IOS(5_0) __TVOS_PROHIBITED; // userInfo contains an NSArray of NKAssetDownload identifiers
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsBluetoothCentralsKey NS_AVAILABLE_IOS(7_0); // userInfo contains an NSArray of CBCentralManager restore identifiers
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsBluetoothPeripheralsKey NS_AVAILABLE_IOS(7_0); // userInfo contains an NSArray of CBPeripheralManager restore identifiers
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsShortcutItemKey NS_AVAILABLE_IOS(9_0) __TVOS_PROHIBITED; // userInfo contains the UIApplicationShortcutItem used to launch the app.
// Key in options dict passed to application[will | did]FinishLaunchingWithOptions and info for UIApplicationDidFinishLaunchingNotification
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsUserActivityDictionaryKey NS_AVAILABLE_IOS(8_0); // Sub-Dictionary present in launch options when user activity is present
UIKIT_EXTERN NSString *const UIApplicationLaunchOptionsUserActivityTypeKey NS_AVAILABLE_IOS(8_0); // Key in user activity dictionary for the activity type
UIKIT_EXTERN NSString *const UIApplicationOpenSettingsURLString NS_AVAILABLE_IOS(8_0);//打开系统定位
// Keys for application:openURL:options:
UIKIT_EXTERN NSString *const UIApplicationOpenURLOptionsSourceApplicationKey NS_AVAILABLE_IOS(9_0); // value is an NSString containing the bundle ID of the originating application
UIKIT_EXTERN NSString *const UIApplicationOpenURLOptionsAnnotationKey NS_AVAILABLE_IOS(9_0); // value is a property-list typed object corresponding to what the originating application passed in UIDocumentInteractionController‘s annotation property
UIKIT_EXTERN NSString *const UIApplicationOpenURLOptionsOpenInPlaceKey NS_AVAILABLE_IOS(9_0); // value is a bool NSNumber, set to YES if the file needs to be copied before use
// Content size category constants //内容大小类别常数
UIKIT_EXTERN NSString *const UIContentSizeCategoryExtraSmall NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategorySmall NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryMedium NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryLarge NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryExtraLarge NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryExtraExtraLarge NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryExtraExtraExtraLarge NS_AVAILABLE_IOS(7_0);
// Accessibility sizes //可访问行
UIKIT_EXTERN NSString *const UIContentSizeCategoryAccessibilityMedium NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryAccessibilityLarge NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryAccessibilityExtraLarge NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryAccessibilityExtraExtraLarge NS_AVAILABLE_IOS(7_0);
UIKIT_EXTERN NSString *const UIContentSizeCategoryAccessibilityExtraExtraExtraLarge NS_AVAILABLE_IOS(7_0);
// Notification is emitted when the user has changed the preferredContentSizeCategory for the system //通知发出时，改变了用户对系统的preferredcontentsizecategory
UIKIT_EXTERN NSString *const UIContentSizeCategoryDidChangeNotification NS_AVAILABLE_IOS(7_0); // userInfo dictionary will contain new value for UIContentSizeCategoryNewValueKey
UIKIT_EXTERN NSString *const UIContentSizeCategoryNewValueKey NS_AVAILABLE_IOS(7_0); // NSString instance with new content size category in userInfo
// This notification is posted after the user takes a screenshot (for example by pressing both the home and lock screen buttons)//此通知发布后，用户需要一个截图(例如，通过按下home键和锁屏按钮)
UIKIT_EXTERN NSString *const UIApplicationUserDidTakeScreenshotNotification NS_AVAILABLE_IOS(7_0);
// Extension point identifier constants //扩展点标识符常量
UIKIT_EXTERN NSString *const UIApplicationKeyboardExtensionPointIdentifier NS_AVAILABLE_IOS(8_0);
NS_ASSUME_NONNULL_END