我已经寻找这个问题的答案很长一段时间了,所以我想我愿意冒着一些失败的风险来发布它。
基本上,我想让Apple提供的用于Apple Watch后台刷新的示例代码实际工作(链接和代码如下)。
我在模拟器和苹果手表系列2的iPhone 6s上都试过了,后台任务从来没有成功完成到时间更新的地步。我尝试将手表应用程序固定在码头上,并尝试将应用程序保持在前台并将其发送到后台,无论是在模拟器中还是在实际的手表上。我甚至试着等了将近一年,看看Xcode或Apple Watch是否会收到更新,让它正常工作。
有没有人成功地修改了Apple提供的代码,使其正常工作?
您可以在此处下载整个runnable示例项目:WatchBackgroundRefresh: Using WKRefreshBackgroundTask to update WatchKit apps in the background
/*
Copyright (C) 2016-2017 Apple Inc. All Rights Reserved.
See LICENSE.txt for this sample’s licensing information
Abstract:
The main interface controller.
*/
import WatchKit
import Foundation
class MainInterfaceController: WKInterfaceController, WKExtensionDelegate, URLSessionDownloadDelegate {
// MARK: Properties
let sampleDownloadURL = URL(string: "http://devstreaming.apple.com/videos/wwdc/2015/802mpzd3nzovlygpbg/802/802_designing_for_apple_watch.pdf?dl=1")!
@IBOutlet var timeDisplayLabel: WKInterfaceLabel!
private let dateFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.dateStyle = .none
formatter.timeStyle = .long
return formatter
}()
// MARK: WKInterfaceController
override func awake(withContext context: Any?) {
super.awake(withContext: context)
// Configure interface objects here.
WKExtension.shared().delegate = self
updateDateLabel()
}
// MARK: WKExtensionDelegate
func handle(_ backgroundTasks: Set<WKRefreshBackgroundTask>) {
for task : WKRefreshBackgroundTask in backgroundTasks {
print("received background task: ", task)
// only handle these while running in the background
if (WKExtension.shared().applicationState == .background) {
if task is WKApplicationRefreshBackgroundTask {
// this task is completed below, our app will then suspend while the download session runs
print("application task received, start URL session")
scheduleURLSession()
}
}
else if let urlTask = task as? WKURLSessionRefreshBackgroundTask {
let backgroundConfigObject = URLSessionConfiguration.background(withIdentifier: urlTask.sessionIdentifier)
let backgroundSession = URLSession(configuration: backgroundConfigObject, delegate: self, delegateQueue: nil)
print("Rejoining session ", backgroundSession)
}
// make sure to complete all tasks, even ones you don't handle
task.setTaskCompleted()
}
}
// MARK: Snapshot and UI updating
func scheduleSnapshot() {
// fire now, we're ready
let fireDate = Date()
WKExtension.shared().scheduleSnapshotRefresh(withPreferredDate: fireDate, userInfo: nil) { error in
if (error == nil) {
print("successfully scheduled snapshot. All background work completed.")
}
}
}
func updateDateLabel() {
let currentDate = Date()
timeDisplayLabel.setText(dateFormatter.string(from: currentDate))
}
// MARK: URLSession handling
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
print("NSURLSession finished to url: ", location)
updateDateLabel()
scheduleSnapshot()
}
func scheduleURLSession() {
let backgroundConfigObject = URLSessionConfiguration.background(withIdentifier: NSUUID().uuidString)
backgroundConfigObject.sessionSendsLaunchEvents = true
let backgroundSession = URLSession(configuration: backgroundConfigObject)
let downloadTask = backgroundSession.downloadTask(with: sampleDownloadURL)
downloadTask.resume()
}
// MARK: IB actions
@IBAction func ScheduleRefreshButtonTapped() {
// fire in 20 seconds
let fireDate = Date(timeIntervalSinceNow: 20.0)
// optional, any SecureCoding compliant data can be passed here
let userInfo = ["reason" : "background update"] as NSDictionary
WKExtension.shared().scheduleBackgroundRefresh(withPreferredDate: fireDate, userInfo: userInfo) { (error) in
if (error == nil) {
print("successfully scheduled background task, use the crown to send the app to the background and wait for handle:BackgroundTasks to fire.")
}
}
}
}
以下是在模拟器上运行时的输出。在其他配置中运行时输出相似(但不一定完全相同):
successfully scheduled background task, use the crown to send the app to the background and wait for handle:BackgroundTasks to fire.
received background task: <WKSnapshotRefreshBackgroundTask: 0x7b019030>
received background task: <WKApplicationRefreshBackgroundTask: 0x7a711290>
application task received, start URL session
https://stackoverflow.com/questions/46086536
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