How to track user location in background?

问题:

I'm looking for an open source app or library to track user location in the background. Now I'm trying to do it with CLLocation and background tasks, but accuracy is not enough for my case. Could you explain, how apps, like "moves", "runkeeper", "endmondo", creates my route? Should I use Accelerometer or/and compass to create a route between CLLocation background points?

Some code:

//location manager init
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.distanceFilter = kCLDistanceFilterNone;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.delegate = self;


#pragma mark - CLLocationManager Delegate

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {

    if ([self isInBackground]) {
        if (self.locationUpdatedInBackground) {
            bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler: ^{
                [[UIApplication sharedApplication] endBackgroundTask:bgTask];
            }];

            self.locationUpdatedInBackground(newLocation);
            [self endBackgroundTask];
        }
    } else {
        if (self.locationUpdatedInForeground) {
            self.locationUpdatedInForeground(newLocation);
        }
    }
}

UPD: Justed tested my app with next properties

self.locationManager.distanceFilter = kCLDistanceFilterNone;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.activityType = CLActivityTypeFitness;
self.locationManager.pausesLocationUpdatesAutomatically=NO;

In this case I have about 10 fired events during 1,5 hour trip

回答1:

Use

kCLLocationAccuracyBestForNavigation

check this.

回答2:

You need to add in your "Info.plist" file the key UIBackgroundModes (array) with the value "location" (app registers for location updates). You can check all background modes here.

回答3:

So your app uses location services. Then please read the Location Awareness Programming Guide.

You need to make some changes to your Info.plist:

• If your app relies on location services to function properly, add location-services to UIRequiredDeviceCapabilities
• if your app requires GPS hardware, add gps to UIRequiredDeviceCapabilities
• if you need to run your app longer then 10 minutes in the background, add location to UIBackgroundModes. Then your location manager will deliver locations beyond the 10-minute-limit.
• you should also set NSLocationUsageDescription (can also be localized)

Getting Location Events in the Background

If your app needs location updates delivered whether the app is in the foreground or background, there are multiple options for doing so. The preferred option is to use the significant location change service to wake your app at appropriate times to handle new events. However, if your app needs to use the standard location service, you can declare your app as needing background location services.

An app should request background location services only if the absence of those services would impair its ability to operate. In addition, any app that requests background location services should use those services to provide a tangible benefit to the user. For example, a turn-by-turn navigation app would be a likely candidate for background location services because of its need to track the user’s position and report when it is time to make the next turn.

回答4:

Your problem is the background handler. Remove it and enable gps background mode in plist file. then you should get full power gps all the time.

Set property pausesLocationUpdatesAutomatically=NO

This is new in ios6.

From CLLocationManager:

Allowing the location manager to pause updates can improve battery life on the target device without sacrificing location data. When this property is set to YES, the location manager pauses updates (and powers down the appropriate hardware) at times when the location data is unlikely to change. For example, if the user stops for food while using a navigation app, the location manager might pause updates for a period of time. You can help the determination of when to pause location updates by assigning a value to the activityType property.

The default value of this property is YES.

For analysis add these methods to your LocationManager delegate:

- (void)locationManagerDidPauseLocationUpdates:(CLLocationManager *)manager {
     NSLog(@"locMan: locationManagerDidPauseLocationUpdates");
}

- (void)locationManagerDidResumeLocationUpdates:(CLLocationManager *)manager {
    NSLog(@"locMan: locationManagerDidResumeLocationUpdates");
}

回答5:

You can set up monitoring location stuff in you VC as below

in viewDidLoad method do as below

CLLocationManager locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;(Accuracy according to your need)
[locationManager startUpdatingLocation];

than you have to overrite below two optional delegate methods of CLLocationManagerDelegate protocol

for iOS6+

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{}

and for iOS 2 to 6

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation

in these methods you will get updated location. use it as you want. every time location updated these method get calls.

回答6:

you don't ask for code. You ask for: "I'm looking for an open source app or library"

It may help you to visit this website.

hope it helps you,

Also a tutorial.

回答7:

Here was my solution to this,

Declare the instance variable:

CLLocationManager *locationManager;

Be sure to include the delegate

<CLLocationManagerDelegate>

In viewDidLoad:

locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move, location is updated
locationManager.desiredAccuracy = kCLLocationAccuracyBest; // get best current locaton coords
locationManager.headingFilter = 1;
[locationManager startUpdatingLocation];
[locationManager startUpdatingHeading];

Implement the delegate method:

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    int degrees = newLocation.coordinate.latitude;
    double decimal = fabs(newLocation.coordinate.latitude - degrees);
    int minutes = decimal * 60;
    double seconds = decimal * 3600 - minutes * 60;
    NSString *lat = [NSString stringWithFormat:@"%d° %d' %1.4f\"",
                     degrees, minutes, seconds];
    NSLog(@" Current Latitude : %@",lat);
    latitudeLocation.text = lat;
    degrees = newLocation.coordinate.longitude;
    decimal = fabs(newLocation.coordinate.longitude - degrees);
    minutes = decimal * 60;
    seconds = decimal * 3600 - minutes * 60;
    NSString *longt = [NSString stringWithFormat:@"%d° %d' %1.4f\"",
                       degrees, minutes, seconds];
    NSLog(@" Current Longitude : %@",longt);
    longitudeLocation.text = longt;
}

回答8:

Disclaimer: I work for Cintric

We also wanted to be able to accurately track a users location in background (even after the app had been killed). We spent a long time solving the problem, especially focusing on battery drain.

We posted a great blog post on how we solved it. And also are providing a drag and drop SDK solution. It's not open source but you can integrate it for free:

You can download the .framework file, drag it into your project and initialize with one line of code: [CintricFind initWithApiKey:@"YOUR_API_KEY_HERE" andSecret:@"YOUR_SECRET_HERE"];

You can get an API key for free. There are docs explaining everything here.