CLLocationManager delegates not working after initialization - iphone

Question

I am trying to get the compass of the iphone to work using the rhomobile framework.
I already did the rhomobile part, created a working wrapper that calls native methods on the iphone, but I cant manage to get the events to work.
Locationmanager.h
#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>
#interface locationController : NSObject <CLLocationManagerDelegate>
{
CLLocationManager *locationManager;
}
#property (strong, nonatomic) CLLocationManager *locationManager;
- (id)init;
- (void)dealloc;
#end
Locationmanager.m
#import "Locationmanager.h"
#include "ruby/ext/rho/rhoruby.h"
//store the values
double gx, gy, gz, gth;
//init location
locationController *lc;
#implementation locationController
#synthesize locationManager;
- (id)init {
if (self = [super init]) {
self.locationManager = [[CLLocationManager alloc] init];
NSLog(#"%#", [CLLocationManager headingAvailable]? #"\n\nHeading available!\n" : #"\n\nNo heading..\n");
NSLog(#"%#", [CLLocationManager locationServicesEnabled]? #"\n\nLocation available!\n" : #"\n\nNo location..\n");
// check if the hardware has a compass
if ([CLLocationManager headingAvailable] == NO) {
// No compass is available. This application cannot function without a compass,
// so a dialog will be displayed and no magnetic data will be measured.
locationManager = nil;
UIAlertView *noCompassAlert = [[UIAlertView alloc] initWithTitle:#"No Compass!" message:#"This device does not have the ability to measure magnetic fields." delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[noCompassAlert show];
[noCompassAlert release];
NSLog(#"\n***** ERROR *****\n No compass found !!!");
} else {
// setup delegate callbacks
locationManager.delegate = self;
// heading service configuration
locationManager.headingFilter = kCLHeadingFilterNone;
// location service configuration
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
//start location services
[locationManager startUpdatingLocation];
// start the compass
[locationManager startUpdatingHeading];
}
return self;
}
}
- (void)dealloc {
[super dealloc];
// Stop the compass
[locationManager stopUpdatingHeading];
[locationManager release];
}
// This delegate method is invoked when the location manager has heading data.
- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)heading {
NSLog(#"\n\n***** New magnetic heading *****\n %f\n", heading.magneticHeading);
NSLog(#"\n\n***** New true heading *****\n %f\n", heading.trueHeading);
gx = heading.x;
gy = heading.y;
gz = heading.z;
gth = heading.trueHeading;
}
// This delegate method is invoked when the location managed encounters an error condition.
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
if ([error code] == kCLErrorDenied) {
// This error indicates that the user has denied the application's request to use location services.
NSLog(#"\n ***** ERROR *****\n Location not allowed!");
[locationManager stopUpdatingHeading];
} else if ([error code] == kCLErrorHeadingFailure) {
NSLog(#"\n ***** ERROR *****\n Magnetic interference or something!");
}
}
#end
//ruby wrappers
void locationmanager_init(void) {
// make sure we can only start this method once
static bool started = false;
if(!started) {
// Initialize the Objective C accelerometer class.
lc = [[locationController alloc] init];
started = true;
}
}
void locationmanager_get_heading(double *x, double *y, double *z, double *th) {
NSLog(#"\n ***** DEBUGGER *****\n Getting heading x: %f, y: %f, z: %f, heading: %f", gx, gy, gz, gth);
*x = gx;
*y = gy;
*z = gz;
*th = gth;
}
I'm running the code on an iphone 4 with iOS 5.1, in the console I can see the debug messages of init, but I never see a debug message of the didUpdateHeading delegate. Anyone got a clue what I missed here?
UPDATE
I think I need to run my code in a background thread to get it working. Currently the locationmanager_init initializes + leaves the code, therefor its not active and the events are not fired.
Anyone got a simple solution initializing this in the background to keep it active?
UPDATE 2
Returned the id, used self = [super init] and still no fix :(
GitHub code
Initializes with locationmanager_init, retrieves data with locationmanager_get_heading

Answer 1

You have to init the CLLocationManager on the main thread, check this SO here, or run it from a thread with an active run loop, check this SO here, From Apple documentation:
Configuration of your location manager object must always occur on a thread with
an active run loop, such as your application’s main thread.
Make sure your locationController and the CCLocationManager inside it are alive past initialization, check here. I may be wrong here, but from your Github code, it seems that the *lc variable is getting released in the autorelease pool. Try giving it an extra retain.
lc = [[[locationController alloc] init] retain];
I guess this is the cause of your problem. If the object is released you wont get any updates.
Not related to the question but:
You should call [super dealloc] last but not first, check this SO here
Put the return statement in your init method before the last parenthesis, and not before the second last.
...
// start the compass
[locationManager startUpdatingHeading];
}
}
return self;
}

Answer 2

- (void)locationManager:(CLLocationManager *)manager
didUpdateHeading:(CLHeading *)heading;
- (void)locationManager:(CLLocationManager *)manager
didFailWithError:(NSError *)error;
These are your instance methods not delegate methods.
check
https://developer.apple.com/library/mac/#documentation/CoreLocation/Reference/CLLocationManagerDelegate_Protocol/CLLocationManagerDelegate/CLLocationManagerDelegate.html

Answer 3

Possibly this is not the solution to the overall problem, but your init method is missing a return statement:
- (id)init {
if (self = [super init]) {
// do your setup here
}
return self;
}