Make a compass iPhone 3GS - ios

Question

I'm making an compass application, but when my function [localManager startUpdatingHeading], calls it will automatically call the function
-(void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading
But the second function is never called, so my program doesn't work. I run this code on my device and nothing happened. Please help me.
- (void)viewDidLoad
{
[super viewDidLoad];
CLLocationManager *locaManager = [[CLLocationManager alloc] init];
locaManager.desiredAccuracy = kCLLocationAccuracyBest;
locaManager.delegate = self;
locaManager.headingFilter = .5;
if ([CLLocationManager locationServicesEnabled] && [CLLocationManager
headingAvailable]) {
[locaManager startUpdatingHeading];
[locaManager startUpdatingLocation];
} else {
NSLog(#"Error");
}
}
- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading {
if (newHeading.headingAccuracy > 0) {
float magneticHeading = newHeading.magneticHeading;
float trueHeading = newHeading.trueHeading;
label2.text = [NSString stringWithFormat:#"%f", magneticHeading];
label1.text = [NSString stringWithFormat:#"%f", trueHeading];
float heading = -1.0f * M_PI * newHeading.magneticHeading / 180.0f;
imagen.transform = CGAffineTransformMakeRotation(heading);
}
}

Answer 1

Declare this variable in .h file
CLLocationManager *locaManager;
do it in .m file
- (void)viewDidLoad
{
[super viewDidLoad];
locaManager = [[CLLocationManager alloc] init];
locaManager.desiredAccuracy = kCLLocationAccuracyBest;
locaManager.delegate = self;
locaManager.headingFilter = .5;
[locaManager startUpdatingHeading];
[locaManager startUpdatingLocation];
}

Answer 2

CLLocationManager *locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.desiredAccuracy = kCLLocationAccuracyKilometer;
locationManager.headingFilter = kCLHeadingFilterNone;
[locationManager startUpdatingHeading];
[self.view bringSubviewToFront:_compass_image];
- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading
{
// [manager stopUpdatingHeading];
double rotation = newHeading.magneticHeading * 3.14159 / 180;
// CGPoint anchorPoint = CGPointMake(0, -23); // The anchor point for your pin
//[mapView.map setTransform:CGAffineTransformMakeRotation(-rotation)];
[_compass_image setTransform:CGAffineTransformMakeRotation(-rotation)];
// [[mapView.map annotations] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
// MKAnnotationView * view = [mapView.map viewForAnnotation:obj];
//
// [view setTransform:CGAffineTransformMakeRotation(rotation)];
// [view setCenterOffset:CGPointApplyAffineTransform(anchorPoint, CGAffineTransformMakeRotation(rotation))];
//
// }];
}
- (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.
[manager stopUpdatingHeading];
}
else if ([error code] == kCLErrorHeadingFailure)
{
// This error indicates that the heading could not be determined, most likely because of strong magnetic interference.
}
}