I'm using a CLLocationManager to get a users location (primarily running in the background). I create it like so and set the accuracy to best lowest as to have minimal impact on battery.
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.desiredAccuracy = kCLLocationAccuracyThreeKilometers;
I then implement the delegate method:
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
I'm running the application in the simulator and simulate a 'freeway drive'. The location manager delegate method seems to be updating every second which I'm thinking isn't correct as the 'car' is probably not travelling at 3km/sec (in fact it's travelling at 50km/hr).
Is my understanding of this functionality correct or am I missing something? Will this have a large negative impact on battery life? Would this change in real life usage depending on cell tower/GPS/wifi signals?
Related
I am trying to get a users current location using CLLocationManager. It is all working fine however there is a bit of a delay while the app is finding the location and I need to wait for it to complete before allowing the user to send it. Is there some sort of completion handler for [locationManager startUpdatingLocation]; of should I just use a BOOL variable to keep track of it?
You can use CLLocationManagerDelegate method called
- (void)locationManager:(CLLocationManager *)manager
didUpdateLocations:(NSArray *)locations
I am trying to get the users location if user is getting or making a phone call. I can use the CTCallCenter for my calling events.
The if one of the states are firing i am trying to get the location...It works because i see the arrow in top right corner...
But i don´t get a callback from CLLocationmanager:
-(void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
Does somebody know´s why?
UPDATE: Just found the Solution by myself..I have to init the CLLocationManager on the main Thread...it works now
Just found the Solution by myself..I have to init the CLLocationManager on the main Thread...it works now
in my IOS app I am implementing geofencing. In the current implementation I am using code like this:
CLRegion* region3 = [[CLRegion alloc] initCircularRegionWithCenter:coordinates radius:100 identifier:#"region3"];
[self.locationManager startMonitoringForRegion:region desiredAccuracy:kCLLocationAccuracyHundredMeters];
and then I am using these delegate methods:
(void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region{
NSLog(#"didenterregion");
}
(void)locationManager:(CLLocationManager *)manager didExitRegion:(CLRegion *)region{
NSLog(#"didexitregion");
}
(void)locationManager:(CLLocationManager *)manager monitoringDidFailForRegion:(CLRegion *)region withError:(NSError *)error
{NSLog(#"monitoringDidFailForRegion");}
However, this code works fine only for radius bigger than 100m.
Here are some questions:
Apple says that in ios6 and above a radius between 1 and 400m is supported for devices 4s and above. Since I do not care how long it will take for the message to be viewed (like I do not care to see the message when entering the region but I do care to see at a latter if I have passed from that region once) can I use smaller radius? I am interested in something like 50m radius or smaller? (in some regions even 20m will be needed for my case).
I have also think that. Apple says that up to 20 regions could be supported. What are the advantages/ disadvantages of a sollution like this (I haven't implemented it yet but I want your opinion).
The pseudocode would be like this:
Declare the regions - save them in an array
Do not call start monitoring
And then in the delegate method:
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
{
for loop in all my regions {
if ([region containsCoordinate: newLocation.coordinate])
code for entering region
}
}
Would it be slower?
Would it consume more battery? (I think monitoring for regions is not battery consuming)?
Could it be more accurate?
Can I have more than 20 regions since I am not registering for monitor?
Thanks in advance.
1.
I suspect the second (didUpdateToLocation:-based) implementation would be more expensive (in terms of battery life) versus the first implementation, simply because you would only run the code in the first (startMonitoringForRegion:-based) implementation if and only if the device came within the radius of one of the (maximum of 20) regions you're tracking.
Whereas in the second implementation, code has to run each time there's a "didUpdateToLocation:" delegate call (which will happen fairly often) and then the code inside the delegate method will get run.
B.T.W., you say the code works fine for a radius of 100m of above, but then the Apple documentation says it should work in iOS6 with "a radius between 1 and 400m is supported for devices 4s and above."
Is your "100m" number your practical result or is it a limitation of the device you're using (something older than an iPhone 4s or an older iOS version)?
2.
Doing anything in the background does consume battery but Apple has optimized CoreLocation for this somewhat (provided you set the correct flag in your app's info.plist file)
3.
I think both will be about equally accurate, except for the fact it may take up to a few minutes for "startMonitoringForRegion:" to report that the region was entered or exited.
4.
And yeah, in the second implementation, you can have as many regions as you want to track. However, the more code you run in the background, the hotter the battery gets and the more likely it is you're draining the battery faster.
I have an app that makes a call to get the user's location:
-(void)getLocation{
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
}
//SET USER LOCATION
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
self.userLocation = [locations lastObject];
NSLog(#"location in IntroVC %f, %f", self.userLocation.coordinate.latitude, self.userLocation.coordinate.longitude);
}
My question is, because that NSLog keeps spitting out a new location infinitely, when should I stop calling the location? Well I guess its really up to my app's functionality, but doesnt this cause battery drain? If so, I should really look into the best way of stopping the updates.
Your Distance filter of the location manager is set to be kCLDistanceFilterNone. This causes the didUpdateLocations method to be called infinite time.
locationManager.distanceFilter = kCLDistanceFilterNone;
Change this line as
locationManager.distanceFilter = 10;
and try again. Change the value as needed.
So now the didUpdateLocation will not be called infinite times. :)
Hopefully this helps.
Depending on the nature of your app, you may well want to turn location services off when you go into the background or when the screen is locked. These notifications hooks are provided generally in your app delegate file (.m). Yes you are right, location services significantly drain battery and it a highly recommended practice for iOS apps using location services to use it cautiously.
Apple seems to have thought about this and has provided an API that notifies the app only if the user has moved "significantly" Apple the significant change location service. The definition of "moved significantly" varies on various aspects depending on WiFi availability, cell tower availability, GPS availability etc. Luckily all this is obfuscated within this API.
I call this method after updating the location in didupdateloactions, so when my app goes in background it remove location icon from top status bar.
At the bottom (in AppDelegate.m) you can see my CLLocationManager delegate methods, none of them get called. I'm using a GPX file, but even if the regions do not get entered or exited, the delegate method didStartMonitoringForRegion should be called.
SomeOtherClass.m
AppDelegate appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
[appDelegate.locationManager startMonitoringForRegion:regionToMonitor desiredAccuracy:kCLLocationAccuracyNearestTenMeters];
AppDelegate.h
#interface AppDelegate : UIResponder <UIApplicationDelegate,CLLocationManagerDelegate>
#property (nonatomic, retain) CLLocationManager *locationManager;
AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
if (locationManager==nil) {
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
}
return YES;
}
-(void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region {
NSLog(#"Did enter region");
}
-(void)locationManager:(CLLocationManager *)manager didExitRegion:(CLRegion *)region {
NSLog(#"Did exit region");
}
-(void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
NSLog(#"Fail");
NSLog(#"%#", [error description]);
}
-(void)locationManager:(CLLocationManager *)manager didStartMonitoringForRegion:(CLRegion *)region {
NSLog(#"Did start monitoring for region: %#", region.identifier);
}
First of all you should add the following Location manager delegate method, and see if for some reason the region monitoring registration failed:
- (void)locationManager:(CLLocationManager *)manager monitoringDidFailForRegion:(CLRegion *)region withError:(NSError *)error {
NSLog(#"%#",error);
}
Second, the region monitoring is a system shared resource.
The documentation states that it allows you limited number of regions to monitor (not specifying any number unfortunately) and mentioning that if another app register additional regions to monitor, some of your apps monitored regions, might be discarded.
Third, region monitoring is not using any GPS technology. It only uses the cellular antenna of your network operator and whenever you change a cell tower, it fires an system event that loops through all monitored regions and see if a region is within the new area you are now located.
This means that you should expect less accuracy in the service and therefore you should increase the radius you are setting for a region.
Finally if your app is completely terminated and NOT suspended, then your app will receive in the app delegate inside the:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
a UIApplicationLaunchOptionsLocationKey in the launchOptions dictionary.
It's your responsibility then to reinitialize your location manager, get the current location and fire a local push notification to the user, within the limited time your application live state has.
As the app is not going to run normally at that stage, but in a limited background mode state.
Also if you want to test the app in the simulator, you should add a track.gpx file to your project and set the simulator to track mode.
Make sure that the 2 locations you put in the simulator are not very distant (as it might take quite long time for the tracking to complete) and set them in a path, where it will enter your monitored region.
Then see if you get any callbacks.
Do not test it with your device, as you need to actually walk a couple of blocks to see any real interaction with the device :-)
Not entirely sure why it wouldn't receive your callbacks. I'll cover a few things I'm noticing and you can see if they help.
You are not setting the desiredAccuracy or distanceFilter in your location manager. They should default to something, but if your locations in the GPX aren't within the accuracy of the regions, it could just be not getting close enough to trigger.
The method you are using to start monitoring has been deprecated in iOS 6. You can add the accuracy to the location manager and leave that off your call.
It would be helpful to see how you are creating your CLRegion to monitor, regionToMonitor. If it is being created ok as soon as you start monitoring, you should see the hollow purple location arrow show up. You should also receive the delegate call -didStartMonitoringForRegion. If neither of these are showing up, then you probably just have an issue with your location manager setup.
One suggestion would be to create your own location manager class and turn it into a singleton. This will prevent you from accidentally initializing multiple delegates and getting multiple calls. It also gives you one clean class to contain all your callback methods.
I don't see anything wrong with the code you've included, so I'm guessing the problem lies in the code you haven't included. Check to make sure your location manager code is being initialized and make sure your CLRegion is being created correctly. Hope this helps. I'll be happy to update my answer if you include more code and we find out what the true issue is.