小编mat*_*lot的帖子

首先,它说

'UIApplicationDidEnterBackground'已重命名为'UIApplication.didEnterBackgroundNotification'

当我说它时,它说

类型'Notification.Name'(又名'NSNotification.Name')没有成员'UIApplication'

func listenForBackgroundNotification() {
    observer = NotificationCenter.default.addObserver(forName: Notification.Name.UIApplicationDidEnterBackground, object: nil, queue: OperationQueue.main) { [weak self] _ in
        if let weakSelf = self {
            if weakSelf.presentedViewController != nil {
                weakSelf.dismiss(animated: true, completion: nil)
            }
            weakSelf.descriptionTextView.resignFirstResponder()

        }
    }
}