Swift NotificationContentExtension不生效：自定义通知UI无法默认显示

我开发的消息应用用OneSignal实现通知功能，已集成标准的OneSignal NotificationServiceExtension。现在需要通过NotificationContentExtension自定义通知UI，将通知左侧的应用图标替换为消息发送者的头像（暂时没找到更简便的实现方式）。

当前问题：通知送达时显示原生推送UI，只有长按通知后才会加载出自定义UI（加载速度较慢），我需要默认直接显示自定义UI。我认为该问题与OneSignal无关，但暂无法脱离它测试。

环境 #

• iOS 17.0（所有目标版本均为17.0）

代码实现 #

主应用代码（SwiftUI） #

import SwiftUI
import OneSignalFramework

@main
struct qqqqApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

struct ContentView: View {
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundStyle(.tint)
            Text("Hello, world!")
        }
        .padding()
    }
}

class AppDelegate: NSObject, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {

        if #available(iOS 10.0, *) {
                let options: UNAuthorizationOptions = [.alert]
                UNUserNotificationCenter.current().requestAuthorization(options: options) { (authorized, error) in
                    if authorized {
                        let categoryIdentifier = "OSNotificationCarousel"
                        let carouselNext = UNNotificationAction(identifier: "OSNotificationCarousel.next", title: "👉", options: [])
                        let carouselPrevious = UNNotificationAction(identifier: "OSNotificationCarousel.previous", title: "👈", options: [])
                        let carouselCategory = UNNotificationCategory(identifier: categoryIdentifier, actions: [carouselNext, carouselPrevious], intentIdentifiers: [], options: [])
                        UNUserNotificationCenter.current().setNotificationCategories([carouselCategory])
                    }
                }
            }
        
       // Remove this method to stop OneSignal Debugging
       OneSignal.Debug.setLogLevel(.LL_VERBOSE)

       // OneSignal initialization
       OneSignal.initialize("API_KEY", withLaunchOptions: launchOptions)

       // requestPermission will show the native iOS notification permission prompt.
       // We recommend removing the following code and instead using an In-App Message to prompt for notification permission
       OneSignal.Notifications.requestPermission({ accepted in
         print("User accepted notifications: \(accepted)")
       }, fallbackToSettings: true)

       return true
    }
}

NotificationServiceExtension代码 #

import UserNotifications

import OneSignalExtension

class NotificationService: UNNotificationServiceExtension {

    var contentHandler: ((UNNotificationContent) -> Void)?
    var receivedRequest: UNNotificationRequest!
    var bestAttemptContent: UNMutableNotificationContent?

    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
        self.receivedRequest = request
        self.contentHandler = contentHandler
        self.bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)

        if let bestAttemptContent = bestAttemptContent {
            /* DEBUGGING: Uncomment the 2 lines below to check this extension is executing
                          Note, this extension only runs when mutable-content is set
                          Setting an attachment or action buttons automatically adds this */
            // print("Running NotificationServiceExtension")
            // bestAttemptContent.body = "[Modified] " + bestAttemptContent.body

            OneSignalExtension.didReceiveNotificationExtensionRequest(self.receivedRequest, with: bestAttemptContent, withContentHandler: self.contentHandler)
        }
    }

    override func serviceExtensionTimeWillExpire() {
        // Called just before the extension will be terminated by the system.
        // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
        if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
            OneSignalExtension.serviceExtensionTimeWillExpireRequest(self.receivedRequest, with: self.bestAttemptContent)
            contentHandler(bestAttemptContent)
        }
    }
}

NotificationContentExtension代码 #

import UIKit
import UserNotifications
import UserNotificationsUI

class NotificationViewController: UIViewController, UNNotificationContentExtension {

    @IBOutlet var titleLabel: UILabel?
    @IBOutlet var subtitle: UILabel?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any required interface initialization here.
    }
    
    func didReceive(_ notification: UNNotification) {
        self.titleLabel?.text = notification.request.content.title
        self.subtitle?.text = notification.request.content.body
    }

}

NotificationContentExtension的Info.plist配置 #

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>NSExtension</key>
    <dict>
        <key>NSExtensionAttributes</key>
        <dict>
            <key>UNNotificationExtensionDefaultContentHidden</key>
            <true/>
            <key>UNNotificationExtensionCategory</key>
            <string>OSNotificationCarousel</string>
            <key>UNNotificationExtensionInitialContentSizeRatio</key>
            <real>0.3</real>
        </dict>
        <key>NSExtensionMainStoryboard</key>
        <string>MainInterface</string>
        <key>NSExtensionPointIdentifier</key>
        <string>com.apple.usernotifications.content-extension</string>
    </dict>
</dict>
</plist>

内容的提问来源于stack exchange，提问作者f3dm76