Getting user location every n minutes after app goes to background - ios

I am trying to implement the suggestions given in this post.
Unfortunately the steps are not clear to me. I tried implementing those suggestions, but the backgroundTimeRemaining continues to decrease even after I start and stop locationServices. This is how I developed it:
- (void)applicationDidEnterBackground:(UIApplication *)application {
UIApplication* app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
// Start the long-running task and return immediately.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Do the work associated with the task.
self.timer = nil;
[self initTimer];
});
}
initTimer:
- (void)initTimer {
// Create the location manager if this object does not
// already have one.
if (nil == self.locationManager)
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
[self.locationManager startMonitoringSignificantLocationChanges];
if (self.timer == nil) {
self.timer = [NSTimer scheduledTimerWithTimeInterval:0.3
target:self
selector:#selector(checkUpdates:)
userInfo:nil
repeats:YES];
}
}
checkUpdates:
- (void)checkUpdates:(NSTimer *)timer{
UIApplication* app = [UIApplication sharedApplication];
double remaining = app.backgroundTimeRemaining;
if(remaining < 580.0) {
[self.locationManager startUpdatingLocation];
[self.locationManager stopUpdatingLocation];
[self.locationManager startMonitoringSignificantLocationChanges];
}
DbgLog(#"Reminaing %f", app.backgroundTimeRemaining);
}
Does anyone have a suggestion on what might be wrong in my code? Both initTimer and checkUpdates are being called, but only during for the background execution time (+- 10 Mins). I want the app to update the location every n minutes "forever".
My app's UIBackgroundModes is set to location.
UPDATE:
I am now resetting the timer on didUpdateToLocation and didFailWithError. But still the backgroundTimeRemaining keeps decreasing:
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation {
NSLog(#"Did Update Location = %f / %f", [newLocation coordinate].latitude, [newLocation coordinate].longitude);
UIApplication* app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
// Start the long-running task and return immediately.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Do the work associated with the task.
[self initTimer];
});
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
[self.locationManager stopUpdatingLocation];
UIApplication* app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
// Start the long-running task and return immediately.
[self initTimer];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Do the work associated with the task.
});
}
I am also invalidating the timer:
- (void)checkUpdates:(NSTimer *)timer{
UIApplication* app = [UIApplication sharedApplication];
double remaining = app.backgroundTimeRemaining;
if(remaining < 580.0 && remaining > 570.0) {
[self.timer invalidate];
self.timer = nil;
[self.locationManager startUpdatingLocation];
[self.locationManager stopUpdatingLocation];
}
DbgLog(#"*************************Checking for updates!!!!!!!!!!! Reminaing %f", app.backgroundTimeRemaining);
}

To anyone else having a nightmare of a time trying to figure this one out, I have a simple solution.
Study the example from raywenderlich.com. The sample code works perfectly, but unfortunately there's no timer during background location. This will run indefinitely.
Add timer by using this code snippet:
-(void)applicationDidEnterBackground {
[self.locationManager stopUpdatingLocation];
UIApplication* app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
self.timer = [NSTimer scheduledTimerWithTimeInterval:intervalBackgroundUpdate
target:self.locationManager
selector:#selector(startUpdatingLocation)
userInfo:nil
repeats:YES];
}
Just don't forget to add "App registers for location updates" in info.plist.

After some days trying all possible solutions I was finally able to make it work. Here is what was wrong in my solution:
I need to setup 2 UIBackgroundTaskIdentifiers, one for the timer, and another one for the locationManager
On my solution, just add:
UIApplication *app = [UIApplication sharedApplication];
bgTask2 = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask2];
bgTask2 = UIBackgroundTaskInvalid; }];
self.locationManager.delegate = self;
[self.locationManager startUpdatingLocation];

Once you're in the background you can only have 10 minutes of additional time. There is no way to extend that. You should use the location background services instead.

Working Code(Entire Stepwise Code)
Modified scurioni's code
Step 1
Go to project -> Capabilities -> Background Modes -> select Location updates.
Go to Project -> Info -> add a key NSLocationAlwaysUsageDescription with an optional string.
Step 2
Add this code to AppDelegate.m
#interface AppDelegate ()<CLLocationManagerDelegate>
#property (strong, nonatomic) CLLocationManager *locationManager;
#property (strong, nonatomic) NSTimer *timer;
#end
Step 3
Add This Code in to applicationDidEnterBackground method in AppDelegate.m
- (void)applicationDidEnterBackground:(UIApplication *)application {
UIApplication *app = [UIApplication sharedApplication];
__block UIBackgroundTaskIdentifier bgTaskId =
[app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTaskId];
bgTaskId = UIBackgroundTaskInvalid;
}];
dispatch_async( dispatch_get_main_queue(), ^{
self.timer = nil;
[self initTimer];
[app endBackgroundTask:bgTaskId];
bgTaskId = UIBackgroundTaskInvalid;
});
}
- (void)initTimer {
if (nil == self.locationManager)
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
[self.locationManager requestAlwaysAuthorization];
[self.locationManager startMonitoringSignificantLocationChanges];
if (self.timer == nil) {
self.timer = [NSTimer scheduledTimerWithTimeInterval:0.3
target:self
selector:#selector(checkUpdates:)
userInfo:nil
repeats:YES];
}
}
- (void)checkUpdates:(NSTimer *)timer{
UIApplication *app = [UIApplication sharedApplication];
double remaining = app.backgroundTimeRemaining;
if(remaining < 580.0) {
[self.locationManager startUpdatingLocation];
[self.locationManager stopUpdatingLocation];
[self.locationManager startMonitoringSignificantLocationChanges];
}
}
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation {
NSLog(#"Did Update Location = %f / %f", [newLocation coordinate].latitude, [newLocation coordinate].longitude);
[self updateLocationWithLatitude:[newLocation coordinate].latitude andLongitude:[newLocation coordinate].longitude];
UIApplication* app = [UIApplication sharedApplication];
__block UIBackgroundTaskIdentifier bgTask =
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self initTimer];
});
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
[self.locationManager stopUpdatingLocation];
UIApplication *app = [UIApplication sharedApplication];
__block UIBackgroundTaskIdentifier bgTask =
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
[self initTimer];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Do the work associated with the task
});
}
-(void)updateLocationWithLatitude:(CLLocationDegrees)latitude
andLongitude:(CLLocationDegrees)longitude{
//Here you can update your web service or back end with new latitude and longitude
}

Related

Updating Location every x seconds iOS

I'm trying to build an iOS where I can update my location every x seconds and send a notification to update the UI.
I get my location but the update is random. Any ideas how to add the interval ?
here is my code :
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation *location = [locations lastObject];
[self sendNotification :#"long"
:[NSString stringWithFormat:#"%.8f",location.coordinate.longitude]];
[self sendNotification :#"lat"
:[NSString stringWithFormat:#"%.8f",location.coordinate.latitude]];
}
Try this :
declared in .h file
#property (strong, nonatomic) NSDate *lastTimestamp;
- (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(#"update your UI");
}
}
use NSTimer:
//declare global
NSTimer *ShareTimeCheck;
int ShareSecLeft;
implement this method:
-(void)shareTimeChecking{
if (ShareSecLeft==0) {
[ShareTimeCheck invalidate];
ShareTimeCheck=nil;
}else{
ShareSecLeft--;
if (ShareSecLeft==0) {
[ShareTimeCheck invalidate];
ShareTimeCheck=nil;
}
}
}
call this one in ur location update method:
if (ShareSecLeft==0) {
[ShareTimeCheck invalidate];
ShareTimeCheck=nil;
ShareSecLeft=5;
heduledTimerWithTimeInterval:1 target:self selector:#selector(shareTimeChecking) userInfo:nil repeats:YES];
//write ur code to update the ui. or update to server as per ur requirement.
}
In iOS natively we can’t change the interval at which the system updates the user location. IOS updates position regularly every second, if have GPS signal.
If the application is in the foreground, we could simply stop monitoring and again start it after interval, for example using NSTimer. In this case, we have to think about the life of the application. The application runs in the background and during idle stops working.
My final procedure is use NSTimer in the background by using UIApplication:beginBackgroundTaskWithExpirationHandler:. This timer triggers periodically while the application runs in the background. You can view the following example:
#import "AppDelegate.h"
#implementation AppDelegate
BOOL locationStarted = FALSE;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
//set default value after application starts
locationStarted = FALSE;
//create CLLocationManager variable
locationManager = [[CLLocationManager alloc] init];
//set delegate
locationManager.delegate = self;
app = [UIApplication sharedApplication];
return YES;
}
//update location
-(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation{
NSLog(#"Location: %f, %f", newLocation.coordinates.longtitude, newLocation.coordinates.latitude);
}
//run background task
-(void)runBackgroundTask: (int) time{
//check if application is in background mode
if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
//create UIBackgroundTaskIdentifier and create a background task, which starts after time
__block UIBackgroundTaskIdentifier bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
NSTimer* t = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:#selector(startTrackingBg) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
[[NSRunLoop currentRunLoop] run];
});
}
}
//starts when application switches to background
- (void)applicationDidEnterBackground:(UIApplication *)application
{
//check if application status is in background
if ( [UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
NSLog(#"start background tracking from appdelegate");
//start updating location with location manager
[locationManager startUpdatingLocation];
}
//change locationManager status after time
[self runBackgroundTask:20];
}
//starts with background task
-(void)startTrackingBg{
//write background time remaining
NSLog(#"backgroundTimeRemaining: %.0f", [[UIApplication sharedApplication] backgroundTimeRemaining]);
//set default time
int time = 60;
//if locationManager is ON
if (locationStarted == TRUE ) {
//stop update location
[locationManager stopUpdatingLocation];
locationStarted = FALSE;
}else{
//start updating location
[locationManager startUpdatingLocation];
locationStarted = TRUE;
//ime how long the application will update your location
time = 5;
}
[self runBackgroundTask:time];
}
//application switches back from background
- (void)applicationWillEnterForeground:(UIApplication *)application
{
locationStarted = FALSE;
//stop updating
[locationManager stopUpdatingLocation];
}
/*** other methods ***/
- (void)applicationWillResignActive:(UIApplication *)application{}
- (void)applicationDidBecomeActive:(UIApplication *)application{}
- (void)applicationWillTerminate:(UIApplication *)application{}
#end
A simpler solution might be to run the timer loop:
__block UIBackgroundTaskIdentifier bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
[app endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
NSTimer* t = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:#selector(startTrackingBg) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
[[NSRunLoop currentRunLoop] run];
});

IOS Whatsap Kill my Background Localisation APP

I have an application that makes the location trace in background. As soon as I get WhatsApp or the phone my location stops and resumes after seeing the image. Would anyone have information on this problem?
Image
- (void) startUpdatingLocationFonction
{
[self.locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
[self.locationManager setDistanceFilter:kCLDistanceFilterNone];
[self.locationManager startUpdatingLocation];
self.locationManagerStartDate = [NSDate date];
}
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
[AppDelegate sharedInstance].latitude=newLocation.coordinate.latitude;
[AppDelegate sharedInstance].longitude=newLocation.coordinate.longitude;
if (![[FoncGlobal sharedFoncGlobal] isValidLocation:(CLLocation *)newLocation withOldLocation:(CLLocation *)oldLocation])
return;
if ((oldLocation.coordinate.longitude != newLocation.coordinate.longitude)
|| (oldLocation.coordinate.latitude != newLocation.coordinate.latitude))
{
[[FoncGlobal sharedFoncGlobal] upDateTraceUser: [NSString stringWithFormat:#"%.8lf",newLocation.coordinate.latitude]: [NSString stringWithFormat:#"%.8lf",newLocation.coordinate.longitude] :[NSString stringWithFormat:#"%.8lf",newLocation.altitude]:[NSString stringWithFormat:#"%.8lf",newLocation.speed]:0];
}
}
- (void)locationManager:(CLLocationManager *)manager didDetermineState:(CLRegionState)state forRegion:(CLRegion *)region
{
if (_inBackground) {
[self extendBackgroundRunningTime];
}
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
[self extendBackgroundRunningTime];
_inBackground = YES;
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
_inBackground = NO;
}
- (void)extendBackgroundRunningTime {
if (bgTask != UIBackgroundTaskInvalid) {
return;
}
NSLog(#"Attempting to extend background running time");
__block Boolean self_terminate = NO;
bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithName:#"DummyTask" expirationHandler:^{
NSLog(#"Background task expired by iOS");
if (self_terminate) {
[[UIApplication sharedApplication] endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid;
}
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
while (true) {
if ([AppDelegate sharedInstance].startTrack)
[self startUpdatingLocationFonction];
[NSThread sleepForTimeInterval:3];
}
});
}

Could a selector on an NSTimer *ever* get executed in the background?

Specifically, I'm looking at the case where the backgrounded app receives a location services update (significant location change). What exactly happens on the background in this scenario? Can any user code run, including pending timers?
You can do it like below using the background Task and Timer:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
[self.locationManager startUpdatingLocation];
return YES;
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
self.bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
[[UIApplication sharedApplication] endBackgroundTask:self.bgTask];
self.bgTask = UIBackgroundTaskInvalid;
}];
self.timer = [NSTimer scheduledTimerWithTimeInterval:60
target:self
selector:#selector(changeAccuracy)
userInfo:nil
repeats:YES];
}
- (void) changeAccuracy {
[self.locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
[self.locationManager setDistanceFilter:kCLDistanceFilterNone];
}
-(void)locationManager:(CLLocationManager *)lm didUpdateLocations:(NSArray *)locations{
CLLocation *location = [locations lastObject];
NSLog(#"Location returned: %f, %f Accuracy: %f", location.coordinate.latitude, location.coordinate.longitude, location.horizontalAccuracy);
[lm setDesiredAccuracy:kCLLocationAccuracyThreeKilometers];
[lm setDistanceFilter:99999];
}

ios, get location every hour (ios7)

In my project I need to get location evry hour. My code looks like this:
#import "AppDelegate.h"
#implementation AppDelegate {
UIBackgroundTaskIdentifier bgTask;
CLLocationManager *locationManager;
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.pausesLocationUpdatesAutomatically = NO;
locationManager.activityType = CLActivityTypeOther;
locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
locationManager.distanceFilter = kCLDistanceFilterNone;
return YES;
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
__block UIBackgroundTaskIdentifier background_task;
background_task = [application beginBackgroundTaskWithExpirationHandler:^ {
[application endBackgroundTask: background_task];
background_task = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[locationManager startUpdatingLocation];
while(TRUE)
{
NSLog(#"Background time Remaining: %f",[[UIApplication sharedApplication] backgroundTimeRemaining]);
[NSThread sleepForTimeInterval:200]; //wait for x sec
[locationManager startUpdatingLocation];
}
[application endBackgroundTask: background_task];
background_task = UIBackgroundTaskInvalid;
});
}
- (void) locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
CLLocation *location = [locations lastObject];
NSDate* eventDate = location.timestamp;
NSTimeInterval time = [eventDate timeIntervalSinceNow];
if (abs(time) < 15.0) {
if (location != nil) {
NSString *lat = [NSString stringWithFormat:#"%.8f", location.coordinate.latitude];
NSString *lng = [NSString stringWithFormat:#"%.8f", location.coordinate.longitude];
NSLog(#"location update ...");
//[APIConnection SaveMyPositionWitLat:lat withLng:lng];
//[locationManager stopUpdatingLocation];
}
}
}
This works, but battery im my phone is drained very fast and location is checking every second. If I enable:
[locationManager stopUpdatingLocation];
then location service is stoped permanently. How to change this code for saving battery power ?
Your idea about getting the location is not really possible in iOS since your app needs a active location monitoring to keep running in the background.
For this Apple has the methods to check only major changes, startMonitoringSignificantLocationChanges.
This will inform you app of any major changes in location. Then what you could do to get a more accurate location is start the normal startUpdatingLocation.
This way you save battery and only grab the location when needed.
can you set locationManager.pausesLocationUpdatesAutomatically to YES this should help

Tracking User Location in the Background in iOS 7

I am trying to track's user location when the application moves to background. I just need to track once. So, I am not using background location services. In the code below this works when I uncomment 1 but it doesn't work when I uncomment 2.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
// 1 works here [self startStandardUpdates];
self.bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
[application endBackgroundTask:self.bgTask];
self.bgTask = UIBackgroundTaskInvalid;
}];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0), ^{
// 2 doesn't work here [self startStandardUpdates];
});
}
In second case this delegate function is not called.
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
NSLog(#"Updated\n%#",locations);
[self.manager stopUpdatingLocation];
[[UIApplication sharedApplication] endBackgroundTask:self.bgTask];
self.bgTask = UIBackgroundTaskInvalid;
}
Can someone tell me why this is not working in 2nd case. Also, is it fine using [self startStandardUpdates] in the first position ?
Try this
By default, this is YES for applications linked against iOS 6.0 or later.
if ([self.manager respondsToSelector:#selector(pausesLocationUpdatesAutomatically)]) {
self.manager.pausesLocationUpdatesAutomatically = NO;
}

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