ios - 使用未声明的类型 'UNUserNotificationCenter'

Question

我想在应用程序处于前台时显示推送通知的横幅。我实现了这个方法来显示通知:

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

但收到此错误使用未声明的类型“UNUserNotificationCenter”

Answer 1

您所要做的就是导入 UserNotifications框架:

import UserNotifications

此外，请确保您符合 UNUserNotificationCenterDelegate .作为一种好的做法，我建议通过将其实现为 extension 来做到这一点:

_{如果您不熟悉委派，您可能需要查看 this出。}

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])
    }
}