Question

我想在应用后台获取用户的位置。如果我使用9秒或更短秒的计时器，它工作正常。如果我使用10秒甚至更长时间，我就无法获得用户的位置......

我的AppDelegate.swift：

import UIKit
import CoreLocation

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, CLLocationManagerDelegate {
    var window: UIWindow?
    var backgroundTaskIdentifier: UIBackgroundTaskIdentifier = UIBackgroundTaskInvalid
    var myTimer: NSTimer?

    var locationManager = CLLocationManager()

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }

    func isMultitaskingSupported() -> Bool {
        return UIDevice.currentDevice().multitaskingSupported
    }

    func timerMethod(sender: NSTimer) {
        let backgroundTimerRemainig = UIApplication.sharedApplication().backgroundTimeRemaining

        self.locationManager.startUpdatingLocation()

        if backgroundTimerRemainig == DBL_MAX {
            println("test1")
        } else {
            println("test")
            self.locationManager.delegate = self
            self.locationManager.startUpdatingLocation()
        }
    }

    func applicationWillResignActive(application: UIApplication) {

    }

    func applicationDidEnterBackground(application: UIApplication){
        if !isMultitaskingSupported() {
            return
        }

        myTimer = NSTimer.scheduledTimerWithTimeInterval(60.0,
            target: self,
            selector: "timerMethod:",
            userInfo: nil,
            repeats: true)

        backgroundTaskIdentifier = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler {
            () -> Void in
            UIApplication.sharedApplication().endBackgroundTask(self.backgroundTaskIdentifier)
        }
    }

    func endBackgroundTask() {
        let mainQueue = dispatch_get_main_queue()

        dispatch_async(mainQueue) { 
            [weak self] in
            if let timer = self!.myTimer {
                timer.invalidate()
                self!.myTimer = nil
                UIApplication.sharedApplication().endBackgroundTask(self!.backgroundTaskIdentifier)
                self!.backgroundTaskIdentifier = UIBackgroundTaskInvalid
            }
        }
    }

    func applicationWillEnterForeground(application: UIApplication) {
        if backgroundTaskIdentifier != UIBackgroundTaskInvalid {
            endBackgroundTask()
        }
    }

    func applicationDidBecomeActive(application: UIApplication) {

    }

    func applicationWillTerminate(application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    }

    func locationManager(manager: CLLocationManager!, didUpdateToLocation locations: [AnyObject]) {
        var latValue = locationManager.location.coordinate.latitude
        var lonValue = locationManager.location.coordinate.longitude
    }
}

为什么当我使用10秒甚至更长时间时，我无法获得用户的位置？

Answer 1

因为在致电didEnterBackground后大约10秒后，该应用会被暂停。

该应用程序位于后台，但未执行代码。系统将应用程序自动移动到此状态，并且之前不会通知它们这样做。暂停时，应用程序仍保留在内存中但不会执行任何代码。

这是iOS app lifecycle。

如果您想在后台获取位置更新，您有两种选择：

background task - 但它只会使应用最多运行3分钟
Run update locations background mode。

应用程序位置在iOS 8的后台

1 个答案: