使用未声明的类型“UNUserNotificationCenter”

您只需导入 UserNotifications

import UserNotifications

此外,确保您符合 UNUserNotificationCenterDelegate 作为一种良好的做法,我建议将其作为 extension :

_{如果你不熟悉 代表团 ,您可能需要检查 this}

import UIKit
// add this:
import UserNotifications

class ViewController: UIViewController {
    .
    .
    .

    // somewhere in your code:
    UNUserNotificationCenter.current().delegate = delegateObject
}

// add this:
// MARK:- UserNotifications
extension ViewController: UNUserNotificationCenterDelegate {
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void)
    {
        completionHandler([.alert, .badge, .sound])
    }
}