我正在寻找一种方法来获得背景位置更新每n分钟在我的iOS应用程序。我使用的是iOS 4.3，解决方案应该适用于未越狱的iphone。
我尝试/考虑了以下选项:
CLLocationManager startUpdatingLocation/startMonitoringSignificantLocationChanges: This works in the background as expected, based on the configured properties, but it seems not possible to force it to update the location every n minutes
NSTimer: Does work when the app is running in the foreground but doesn't seem to be designed for background tasks
Local notifications: Local notifications can be scheduled every n minutes, but it's not possible to execute some code to get the current location (without the user having to launch the app via the notification). This approach also doesn't seem to be a clean approach as this is not what notifications should be used for.
UIApplication:beginBackgroundTaskWithExpirationHandler: As far as I understand, this should be used to finish some work in the background (also limited in time) when an app is moved to the background rather than implementing "long-running" background processes.
如何实现这些定期的后台位置更新?
I did this in an application I'm developing. The timers don't work when the app is in the background but the app is constantly receiving the location updates. I read somewhere in the documentation (i can't seem to find it now, i'll post an update when i do) that a method can be called only on an active run loop when the app is in the background. The app delegate has an active run loop even in the bg so you dont need to create your own to make this work.
[Im not sure if this is the correct explanation but thats how I understood from what i read]
首先，在应用的info.plist中添加关键UIBackgroundModes的location对象。现在，你需要做的是启动位置更新在你的应用程序的任何地方:
CLLocationManager locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;//or whatever class you have for managing location
[locationManager startUpdatingLocation];
Next, write a method to handle the location updates,
say -(void)didUpdateToLocation:(CLLocation*)location, in the app delegate. Then implement the method locationManager:didUpdateLocation:fromLocation of CLLocationManagerDelegate in the class in which you started the location manager (since we set the location manager delegate to 'self'). Inside this method you need to check if the time interval after which you have to handle the location updates has elapsed. You can do this by saving the current time every time. If that time has elapsed, call the method UpdateLocation from your app delegate:
NSDate *newLocationTimestamp = newLocation.timestamp;
NSDate *lastLocationUpdateTiemstamp;
int locationUpdateInterval = 300;//5 mins
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
if (userDefaults) {
lastLocationUpdateTiemstamp = [userDefaults objectForKey:kLastLocationUpdateTimestamp];
if (!([newLocationTimestamp timeIntervalSinceDate:lastLocationUpdateTiemstamp] < locationUpdateInterval)) {
//NSLog(@"New Location: %@", newLocation);
[(AppDelegate*)[UIApplication sharedApplication].delegate didUpdateToLocation:newLocation];
[userDefaults setObject:newLocationTimestamp forKey:kLastLocationUpdateTimestamp];
}
}
}
这将每5分钟调用你的方法，即使你的应用程序是在后台。
Imp:这个实现耗尽电池，如果你的位置数据的准确性不是关键，你应该使用[locationManager startMonitoringSignificantLocationChanges]
在将此添加到应用程序之前，请阅读位置感知编程指南
以下是我使用的方法:
import Foundation
import CoreLocation
import UIKit
class BackgroundLocationManager :NSObject, CLLocationManagerDelegate {
static let instance = BackgroundLocationManager()
static let BACKGROUND_TIMER = 150.0 // restart location manager every 150 seconds
static let UPDATE_SERVER_INTERVAL = 60 * 60 // 1 hour - once every 1 hour send location to server
let locationManager = CLLocationManager()
var timer:NSTimer?
var currentBgTaskId : UIBackgroundTaskIdentifier?
var lastLocationDate : NSDate = NSDate()
private override init(){
super.init()
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyKilometer
locationManager.activityType = .Other;
locationManager.distanceFilter = kCLDistanceFilterNone;
if #available(iOS 9, *){
locationManager.allowsBackgroundLocationUpdates = true
}
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(self.applicationEnterBackground), name: UIApplicationDidEnterBackgroundNotification, object: nil)
}
func applicationEnterBackground(){
FileLogger.log("applicationEnterBackground")
start()
}
func start(){
if(CLLocationManager.authorizationStatus() == CLAuthorizationStatus.AuthorizedAlways){
if #available(iOS 9, *){
locationManager.requestLocation()
} else {
locationManager.startUpdatingLocation()
}
} else {
locationManager.requestAlwaysAuthorization()
}
}
func restart (){
timer?.invalidate()
timer = nil
start()
}
func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {
switch status {
case CLAuthorizationStatus.Restricted:
//log("Restricted Access to location")
case CLAuthorizationStatus.Denied:
//log("User denied access to location")
case CLAuthorizationStatus.NotDetermined:
//log("Status not determined")
default:
//log("startUpdatintLocation")
if #available(iOS 9, *){
locationManager.requestLocation()
} else {
locationManager.startUpdatingLocation()
}
}
}
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
if(timer==nil){
// The locations array is sorted in chronologically ascending order, so the
// last element is the most recent
guard let location = locations.last else {return}
beginNewBackgroundTask()
locationManager.stopUpdatingLocation()
let now = NSDate()
if(isItTime(now)){
//TODO: Every n minutes do whatever you want with the new location. Like for example sendLocationToServer(location, now:now)
}
}
}
func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {
CrashReporter.recordError(error)
beginNewBackgroundTask()
locationManager.stopUpdatingLocation()
}
func isItTime(now:NSDate) -> Bool {
let timePast = now.timeIntervalSinceDate(lastLocationDate)
let intervalExceeded = Int(timePast) > BackgroundLocationManager.UPDATE_SERVER_INTERVAL
return intervalExceeded;
}
func sendLocationToServer(location:CLLocation, now:NSDate){
//TODO
}
func beginNewBackgroundTask(){
var previousTaskId = currentBgTaskId;
currentBgTaskId = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler({
FileLogger.log("task expired: ")
})
if let taskId = previousTaskId{
UIApplication.sharedApplication().endBackgroundTask(taskId)
previousTaskId = UIBackgroundTaskInvalid
}
timer = NSTimer.scheduledTimerWithTimeInterval(BackgroundLocationManager.BACKGROUND_TIMER, target: self, selector: #selector(self.restart),userInfo: nil, repeats: false)
}
}
我像这样在AppDelegate中开始跟踪:
BackgroundLocationManager.instance.start()
不幸的是，你所有的假设似乎都是正确的，我认为没有办法做到这一点。为了节省电池寿命，iPhone的定位服务是基于移动的。如果手机放在一个位置，定位服务就看不见它。
CLLocationManager只会在手机接收到位置更新时调用locationManager:didUpdateToLocation:fromLocation:，这只会发生在三个位置服务(蜂窝塔，gps, wifi)之一感知到变化时。
其他一些事情可能有助于进一步的解决方案:
Starting & Stopping the services causes the didUpdateToLocation delegate method to be called, but the newLocation might have an old timestamp.
Region Monitoring might help
When running in the background, be aware that it may be difficult to get "full" LocationServices support approved by Apple. From what I've seen, they've specifically designed startMonitoringSignificantLocationChanges as a low power alternative for apps that need background location support, and strongly encourage developers to use this unless the app absolutely needs it.
好运！
更新:这些想法现在可能已经过时了。看起来人们在@wjans的回答上取得了成功。
I did this in an application I'm developing. The timers don't work when the app is in the background but the app is constantly receiving the location updates. I read somewhere in the documentation (i can't seem to find it now, i'll post an update when i do) that a method can be called only on an active run loop when the app is in the background. The app delegate has an active run loop even in the bg so you dont need to create your own to make this work.
[Im not sure if this is the correct explanation but thats how I understood from what i read]
首先，在应用的info.plist中添加关键UIBackgroundModes的location对象。现在，你需要做的是启动位置更新在你的应用程序的任何地方:
CLLocationManager locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;//or whatever class you have for managing location
[locationManager startUpdatingLocation];
Next, write a method to handle the location updates,
say -(void)didUpdateToLocation:(CLLocation*)location, in the app delegate. Then implement the method locationManager:didUpdateLocation:fromLocation of CLLocationManagerDelegate in the class in which you started the location manager (since we set the location manager delegate to 'self'). Inside this method you need to check if the time interval after which you have to handle the location updates has elapsed. You can do this by saving the current time every time. If that time has elapsed, call the method UpdateLocation from your app delegate:
NSDate *newLocationTimestamp = newLocation.timestamp;
NSDate *lastLocationUpdateTiemstamp;
int locationUpdateInterval = 300;//5 mins
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
if (userDefaults) {
lastLocationUpdateTiemstamp = [userDefaults objectForKey:kLastLocationUpdateTimestamp];
if (!([newLocationTimestamp timeIntervalSinceDate:lastLocationUpdateTiemstamp] < locationUpdateInterval)) {
//NSLog(@"New Location: %@", newLocation);
[(AppDelegate*)[UIApplication sharedApplication].delegate didUpdateToLocation:newLocation];
[userDefaults setObject:newLocationTimestamp forKey:kLastLocationUpdateTimestamp];
}
}
}
这将每5分钟调用你的方法，即使你的应用程序是在后台。
Imp:这个实现耗尽电池，如果你的位置数据的准确性不是关键，你应该使用[locationManager startMonitoringSignificantLocationChanges]
在将此添加到应用程序之前，请阅读位置感知编程指南
