iOS系统通知触发响应回调

一、系统iOS 10以下系统

都是一个方法，没有办法区分收到通知和点击通知的具体情况，可以用UIApplicationStateBackground判断前后台的情况

// This method will be invoked even if the application was launched or resumed because of the remote notification. The respective delegate methods will be invoked first. Note that this behavior is in contrast to application:didReceiveRemoteNotification:, which is not called in those cases, and which will not be invoked if this method is implemented. !*/
-  (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler API_AVAILABLE(ios(7.0));

二、系统iOS 10及其以上系统

应用在前台

收到通知：决定呈现形式

// The method will be called on the delegate only if the application is in the foreground. If the method is not implemented or the handler is not called in a timely manner then the notification will not be presented. The application can choose to have the notification presented as a sound, badge, alert and/or in the notification list. This decision should be based on whether the information in the notification is otherwise visible to the user.
- (void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions options))completionHandler __API_AVAILABLE(macos(10.14), ios(10.0), watchos(3.0), tvos(10.0));

点击通知：App正在运行，但是通知栏有消息

// The method will be called on the delegate when the user responded to the notification by opening the application, dismissing the notification or choosing a UNNotificationAction. The delegate must be set before the application returns from application:didFinishLaunchingWithOptions:.
- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void(^)(void))completionHandler

应用在后台

收到通知：开启后台模式

// This method will be invoked even if the application was launched or resumed because of the remote notification. The respective delegate methods will be invoked first. Note that this behavior is in contrast to application:didReceiveRemoteNotification:, which is not called in those cases, and which will not be invoked if this method is implemented. !*/
-  (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler API_AVAILABLE(ios(7.0));

点击通知

// The method will be called on the delegate when the user responded to the notification by opening the application, dismissing the notification or choosing a UNNotificationAction. The delegate must be set before the application returns from application:didFinishLaunchingWithOptions:.
- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void(^)(void))completionHandler

应用退出（杀掉）

收到通知：此处收到通知是执行“App”收到消息的方法，应用退出（即App杀掉）程序方法就不会执行，所以此种情况不存在

点击通知

// The method will be called on the delegate when the user responded to the notification by opening the application, dismissing the notification or choosing a UNNotificationAction. The delegate must be set before the application returns from application:didFinishLaunchingWithOptions:.
- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void(^)(void))completionHandler

总结：iOS10及以上系统

收到通知：分前台和后台模式，前台模式可以决定呈现形式，后台模式需要工程配置Capabilities

前台模式

// The method will be called on the delegate only if the application is in the foreground. If the method is not implemented or the handler is not called in a timely manner then the notification will not be presented. The application can choose to have the notification presented as a sound, badge, alert and/or in the notification list. This decision should be based on whether the information in the notification is otherwise visible to the user.
 - (void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions options))completionHandler __API_AVAILABLE(macos(10.14), ios(10.0), watchos(3.0), tvos(10.0));

后台模式

// This method will be invoked even if the application was launched or resumed because of the remote notification. The respective delegate methods will be invoked first. Note that this behavior is in contrast to application:didReceiveRemoteNotification:, which is not called in those cases, and which will not be invoked if this method is implemented. !*/
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult result))completionHandler API_AVAILABLE(ios(7.0));

点击通知

// The method will be called on the delegate when the user  responded to the notification by opening the application, dismissing the notification or choosing a UNNotificationAction. The delegate must be set before the application returns from application:didFinishLaunchingWithOptions:.
- (void)userNotificationCenter:(UNUserNotificationCenter *)center didReceiveNotificationResponse:(UNNotificationResponse *)response withCompletionHandler:(void(^)(void))completionHandler