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?
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。
似乎stopUpdatingLocation是什么触发后台看门狗定时器，所以我在didUpdateLocation替换它:
[self.locationManager setDesiredAccuracy:kCLLocationAccuracyThreeKilometers];
[self.locationManager setDistanceFilter:99999];
这似乎有效地关闭了GPS。然后，背景NSTimer的选择器变成:
- (void) changeAccuracy {
[self.locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
[self.locationManager setDistanceFilter:kCLDistanceFilterNone];
}
我所做的是每隔几分钟定期切换精度以获得高精度坐标，因为locationManager没有停止，backgroundtimerremain保持在其最大值。这将我的设备上的电池消耗从每小时~10%(在后台使用恒定的kCLLocationAccuracyBest)降低到每小时~2%
在iOS 8/9/10上，每5分钟更新一次后台位置，执行以下操作:
进入项目->能力->背景模式->选择位置更新
转到项目->信息->添加一个键NSLocationAlwaysUsageDescription空值(或可选的任何文本)
当你的应用程序在后台工作，并发送坐标到web服务或做任何事情，每5分钟实现如下代码。
我没有使用任何后台任务或计时器。我在我的iOS 8.1设备上测试了这段代码，我的应用程序在后台运行了几个小时。设备被锁定，代码一直正常运行。
@interface LocationManager () <CLLocationManagerDelegate>
@property (strong, nonatomic) CLLocationManager *locationManager;
@property (strong, nonatomic) NSDate *lastTimestamp;
@end
@implementation LocationManager
+ (instancetype)sharedInstance
{
static id sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[self alloc] init];
LocationManager *instance = sharedInstance;
instance.locationManager = [CLLocationManager new];
instance.locationManager.delegate = instance;
instance.locationManager.desiredAccuracy = kCLLocationAccuracyBest; // you can use kCLLocationAccuracyHundredMeters to get better battery life
instance.locationManager.pausesLocationUpdatesAutomatically = NO; // this is important
});
return sharedInstance;
}
- (void)startUpdatingLocation
{
CLAuthorizationStatus status = [CLLocationManager authorizationStatus];
if (status == kCLAuthorizationStatusDenied)
{
NSLog(@"Location services are disabled in settings.");
}
else
{
// for iOS 8
if ([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)])
{
[self.locationManager requestAlwaysAuthorization];
}
// for iOS 9
if ([self.locationManager respondsToSelector:@selector(setAllowsBackgroundLocationUpdates:)])
{
[self.locationManager setAllowsBackgroundLocationUpdates:YES];
}
[self.locationManager startUpdatingLocation];
}
}
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation *mostRecentLocation = locations.lastObject;
NSLog(@"Current location: %@ %@", @(mostRecentLocation.coordinate.latitude), @(mostRecentLocation.coordinate.longitude));
NSDate *now = [NSDate date];
NSTimeInterval interval = self.lastTimestamp ? [now timeIntervalSinceDate:self.lastTimestamp] : 0;
if (!self.lastTimestamp || interval >= 5 * 60)
{
self.lastTimestamp = now;
NSLog(@"Sending current location to web service.");
}
}
@end
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()
