Question

我已经设置了后台获取，并且通过调试->模拟后台获取可以很好地工作。但是，当涉及到真实设备时，永远都不会被调用！！！我已经等了将近一个星期了，但是没有什么新鲜！

这是我的代码和设置首先：我已从“功能”选项卡中打开了后台获取功能，并在info.plist

中检查了它的反映

<key>UIBackgroundModes</key>
<array>
    <string>fetch</string>
</array>

第二：我在AppDelegate.swift中将UIApplicationBackgroundFetchIntervalMinimum设置为Minimum

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    registerForNotifications()
    UNUserNotificationCenter.current().delegate = self
    UIApplication.shared.setMinimumBackgroundFetchInterval(UIApplicationBackgroundFetchIntervalMinimum)
return true
}

第三：当我在performFetchWithCompletionHandler中调用后台获取时，我正在运行要处理的过程

func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
            let content =  UserNotifications.UNMutableNotificationContent()

    let documentsPath = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
    let destinationSqliteURL = documentsPath.appendingPathComponent("MyDB.db")
    let db = FMDatabase(path: destinationSqliteURL.path)

    if !db.open() {
        print("Unable to open database")
        completionHandler(UIBackgroundFetchResult.failed)
        return
    }
    var title : String!
    if let rs = db.executeQuery("select _Title from Questions ORDER BY RANDOM() LIMIT 1;", withArgumentsIn: []){
        while (rs.next()){
            title = rs.string(forColumn: "_Title")
        }
    } else {
        print("select failed: \(db.lastErrorMessage())")
        completionHandler(UIBackgroundFetchResult.failed)
    }
    content.title = "Q&A of the Day"
    content.body = title!
    content.sound = UNNotificationSound.default()

    var dateComponents = DateComponents()
    dateComponents.calendar = Calendar.current

    dateComponents.hour = 8   // 8:00 hours

    let trigger = UNCalendarNotificationTrigger(
        dateMatching: dateComponents, repeats: true)

    let uuidString = UUID().uuidString
    let request = UNNotificationRequest(identifier: uuidString,
                                        content: content, trigger: trigger)


    let notificationCenter = UNUserNotificationCenter.current()
    notificationCenter.removeAllPendingNotificationRequests()
    notificationCenter.add(request) { (error) in
        if error != nil {
            print("ERROR in setting up the scheduled notification request")
            completionHandler(UIBackgroundFetchResult.failed)
        }
        else{
            print("Notification is Sent")
            completionHandler(UIBackgroundFetchResult.newData)
        }
     }
 }

这在从模拟后台提取中对其进行调试时完美地起作用，但是，即使在真实设备上对其进行测试时也不会被调用。我知道，既然它甚至被调用过一次，那么我应该每天早晨8:00发送一个通知，而在实际设备上则不是这种情况。

迅捷4：从未调用过后台获取

0 个答案: