Ios 应用程序打开时如何获取推送通知？

我正在使用swift 4.2。当应用程序处于后台时，我会收到通知，但当应用程序处于活动状态时，我不会收到通知

func userNotificationCenter（center:unuservificationcenter，将显示通知：UNNotification，with completionHandler completionHandler:@escaping（UNNotificationPresentationOptions）->Void）{
completionHandler（[.alert、.badge、.sound]）
}

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我想知道当应用程序打开时如何获取通知

您需要在AppDelegate类中确认UnuseNotificationCenterDelegate

import UserNotifications

class AppDelegate : UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate

   func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

      UNUserNotificationCenter.current().delegate = self

   }

然后可以在ViewController类中调用此函数，不要忘记在ViewController中再次导入UserNotifications

func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) 
{
    completionHandler([.alert, .badge, .sound])
}

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用上述代码更新此代码

func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler:
        @escaping (UNNotificationPresentationOptions) -> Void) {
        print("Handle push from foreground")
        print("\(notification.request.content.userInfo)")
        completionHandler([.alert, .badge, .sound])

        return
    }

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你为什么不明白？它只是没有显示出来。看你是最幸福的：）