如果应用程序在前台运行，iOS 将不会显示通知横幅/警报。这是设计使然。但是我们可以通过UILocalNotification如下方式来实现

• 在收到远程通知时检查应用程序是否处于活动状态。如果处于活动状态，则触发 UILocalNotification。

  if (application.applicationState == UIApplicationStateActive ) {
  
  UILocalNotification *localNotification = [[UILocalNotification alloc] init];
  localNotification.userInfo = userInfo;
  localNotification.soundName = UILocalNotificationDefaultSoundName;
  localNotification.alertBody = message;
  localNotification.fireDate = [NSDate date];
  [[UIApplication sharedApplication] scheduleLocalNotification:localNotification];
  

  }

迅速：

if application.applicationState == .active {
    var localNotification = UILocalNotification()
    localNotification.userInfo = userInfo
    localNotification.soundName = UILocalNotificationDefaultSoundName
    localNotification.alertBody = message
    localNotification.fireDate = Date()
    UIApplication.shared.scheduleLocalNotification(localNotification)
}