BGAppRefreshTask不执行SwiftUI

Question

在用背景任务框架编写SwiftUI应用程序时，我得到的结果不一致。我只想提出快速的网络请求，所以我选择使用BGAppRefreshTask。

在签名和功能中设置了后台获取和后台处理。已设置允许的后台任务调度程序标识符。在调试中手动调用它可以在实际设备上正常工作，但在生产中则不会。

我测试了BGAppRefreshTask和BGProcessingTask。我注意到BGProcessingTask正在被调用，但只有当连接到电源时才被调用。我从未见过BGAppRefreshTask的任何更新。我不确定我是不是错过了一些简单的东西。

自从更新这篇文章以来，BGAppRefreshTask还没有为运行过四天。BGProcessingTask在一夜之间运行了13次，但前提是我的设备正在充电。即使将requiresExternalPower设置为false时也是如此。

BGAppRefreshTask run: 0 & BGProcessingTask run: 13

使用命令这里调用调试器是有效的，但它在我的设备上运行时必须在调试器中进行模拟。

(lldb) e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:@"com.bgapp.refresh"]
2022-02-26 11:41:33.964753-0800 BGAppRefreshTask[9180:2203525] Simulating launch for task with identifier com.bgapp.refresh
2022-02-26 11:41:35.908739-0800 BGAppRefreshTask[9180:2203542] Starting simulated task: <decode: missing data>
2022-02-26 11:41:35.912108-0800 BGAppRefreshTask[9180:2203542] Marking simulated task complete: <BGAppRefreshTask: com.bgapp.refresh>
Received completion: finished.

更新

我使用getPendingTaskRequests查看是否注册了任何任务，很明显，它正在执行，但仍未执行。最早的日期是19:28，所以7:28PM。我在11:23注册了我的任务，但是没有计划运行另一个8小时。

Pending task requests: [<BGAppRefreshTaskRequest: com.bgapp.refresh, earliestBeginDate: 2022-02-28 19:28:34 +0000>]

BGAppRefresh

/*!
 BGAppRefreshTask
 @abstract A background task used to update your app's contents in the background.
 */
class BGADelegate: NSObject,  UIApplicationDelegate, ObservableObject {
    let taskIdentifier = "com.bgapp.refresh"
    @AppStorage("backgroundtask") var tasks: Int = 0
    
    func application(_ applicatiown: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
        register()
        scheduleAppRefresh()
        return true
    }

    func register() {
        BGTaskScheduler.shared.register(forTaskWithIdentifier: taskIdentifier, using: nil) { task in
            self.handleAppRefresh(task: task as! BGAppRefreshTask)
            print("register")
        }
    }
    
    func scheduleAppRefresh() {
        let request = BGAppRefreshTaskRequest(identifier: taskIdentifier)
        request.earliestBeginDate = Date(timeIntervalSinceNow: 15 * 60)
        do {
            try BGTaskScheduler.shared.submit(request)
        } catch {
            print("Could not schedule app refresh: \(error)")
        }
    }
    
    func handleAppRefresh(task: BGAppRefreshTask) {
        scheduleAppRefresh()
        task.expirationHandler = {
            task.setTaskCompleted(success: false)
        }
        DispatchQueue.main.async {
            self.tasks += 1
        }
        // Network request here
        task.setTaskCompleted(success: true)
        print("handle app refresh")
    }
    
}

BGProcessingTask

/*!
 BGProcessingTask
 @abstract A background task used to perform deferrable processing.
 */
class BGPDelegate: NSObject,  UIApplicationDelegate, ObservableObject {
    let taskIdentifier = "com.bgapp.refresh"
    @AppStorage("backgroundtask") var tasks: Int = 0
    
    func application(_ applicatiown: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
        register()
        scheduleAppRefresh()
        return true
    }

    func register() {
        BGTaskScheduler.shared.register(forTaskWithIdentifier: taskIdentifier, using: nil) { task in
            self.handleAppRefresh(task: task as! BGProcessingTask)
            print("register")
        }
    }
    
    func scheduleAppRefresh() {
        let request = BGProcessingTaskRequest(identifier: taskIdentifier)
        request.earliestBeginDate = Date(timeIntervalSinceNow: 15 * 60)
        request.requiresNetworkConnectivity = true
        request.requiresExternalPower = false // Default value in false
        do {
            try BGTaskScheduler.shared.submit(request)
        } catch {
            print("Could not schedule app refresh: \(error)")
        }
    }
    
    func handleAppRefresh(task: BGProcessingTask) {
        scheduleAppRefresh()
        task.expirationHandler = {
            task.setTaskCompleted(success: false)
        }
        DispatchQueue.main.async {
            self.backgroundtask += 1
        }
        // Network request here
        task.setTaskCompleted(success: true)
        print("handle app refresh")
    }
    
}

Answer 1

因此，根据对Background Tasks的新理解，我知道现在它正在被排定为最早的日期，但我正在打开这个应用程序，将它的日期设置为预定日期。当重新启动应用程序时，我没有等待超过预定的较早日期。设置后台应用程序刷新任务时，每个任务都将被覆盖。

struct BGAppRefreshTaskApp: App {
    @UIApplicationDelegateAdaptor var delegate: AppDelegate
    @Environment(\.scenePhase) var scenePhase
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(delegate)
                .onChange(of: scenePhase) { phase in
                    switch phase {
                    case .background:
                        delegate.scheduleAppRefresh()
                        delegate.background += 1
                        print("background")
                    case .active:
                        print("active")
                        BGTaskScheduler.shared.getPendingTaskRequests(completionHandler: { request in
                            print("Pending task requests: \(request)")
                        })
                    case .inactive:
                        print("inactive")
                    @unknown default:
                        break
                    }
                }
        }
    }
}