swift - 每小时安排后台任务 swift 4

Question

我已经搜索并尝试了太长时间，如何解决我的问题。 我有订单，需要每小时在我的后端 C# 上检查它们的更新。即使在后台状态或前台。

我已经尝试过:

var timer = Timer.scheduledTimer(withTimeInterval: 5.0, repeats: true) {
    timer in
    self.updatePedidos(timer: timer)
}
func updatePedidos() {
    print("background started")
    let strdata = Functions.getMostRecentDtPedido()
    Functions.loadOrdersFromLastSyncByApi(strdata)
}

另外:

func applicationDidEnterBackground(_ application: UIApplication) {
    Timer.scheduledTimer(timeInterval: 0.4, target: self, selector: #selector(self.updatePedidos), userInfo: nil, repeats: true)
}
@objc func updatePedidos() {
    print("background started")
    let strdata = Functions.getMostRecentDtPedido()
    Functions.loadOrdersFromLastSyncByApi(strdata)
}

另外:

func applicationDidEnterBackground(_ application: UIApplication) {
    UIApplication.shared.setMinimumBackgroundFetchInterval( 5 )
}
func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler:
    @escaping (UIBackgroundFetchResult) -> Void) {
    print("background started")
    let strdata = Functions.getMostRecentDtPedido()
    Functions.loadOrdersFromLastSyncByApi(strdata)

    if let newData = fetchUpdates() {
        addDataToFeed(newData: newData)
        completionHandler(.newData)
    }

    completionHandler(.noData)
}

最后我不能设置计时器:

NotificationCenter.default.addObserver(self, selector: #selector(updatePedidos), name:UIApplication.didEnterBackgroundNotification, object: nil)
@objc func updatePedidos() {
    print("background started")
    let strdata = Functions.getMostRecentDtPedido()
    Functions.loadOrdersFromLastSyncByApi(strdata)
}

所有这些都不会在后台状态下打印“后台启动”，而只是在前台打印。我在 info.plist 上添加了:

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

Answer 1

您可以使用静默推送通知来尝试。每小时发送 1 条静默推送通知，并在后台模式下唤醒应用程序并执行您的任务一段时间。

您可以在下面的文章中阅读有关后台任务执行的更多详细信息:

https://www.hackingwithswift.com/example-code/system/how-to-run-code-when-your-app-is-terminated

Is there a way to wakeup suspended app in iOS without user or server intervention