Showing current location in my iphone - ios

Question

I am implementing the route directions from my current location to some destination location.
When I enter in a specific page, my application crashes. But if I run the app again, it shows the route directions.
I found out the problem is that the first time, current location is showing as 0.00000,0.00000 coordinates. The second time I launch the app, current location is showing up correctly.
What is going wrong?
I want to get my current position correctly at first time.
I am writing the code on below. Once please check it out and let me know the where is the problem in my code
#import "MapWithRoutesViewController.h"
#import "TFSViewController.h"
#implementation MapWithRoutesViewController
#synthesize locationManager,lat,lon;
- (void) updateCurrentLabel {
NSObject *latitude = [NSString stringWithFormat:#"%f", locationManager.location.coordinate.latitude];
NSObject *longitude = [NSString stringWithFormat:#"%f", locationManager.location.coordinate.longitude];
locationlable.text = [NSString stringWithFormat: #"Current Location: %#,%#", latitude, longitude];
}
- (void)viewDidLoad {
[self getCurrentLocation];
[super viewDidLoad];
}
-(void) locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
[self updateCurrentLabel];
}
-(void) getCurrentLocation {
MapView* mapView = [[[MapView alloc] initWithFrame:
CGRectMake(0, 90, self.view.frame.size.width, self.view.frame.size.height)] autorelease]; [self.view
addSubview:mapView];
Place* home = [[[Place alloc] init] autorelease];
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
if (locationManager==NO) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Location Service Disabled"
message:#"To re-enable, please go to Settings and turn on Location Service for
this app."
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alert show];
[alert release];
} else {
// if (locationManager==NO)
// [mapView.lo addObserver:self forKeyPath:#"location"
// options:(NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld)
// context:nil];
}
locationManager.pausesLocationUpdatesAutomatically = NO;
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
[locationManager setPausesLocationUpdatesAutomatically:YES];
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
locationManager.distanceFilter = kCLDistanceFilterNone;
[locationManager startUpdatingLocation];
CLLocation *Loc = [locationManager location];
CLLocationCoordinate2D coordinate = [Loc coordinate];
NSObject *latitude = [NSString stringWithFormat:#"%f", locationManager.location.coordinate.latitude];
NSObject *longitude = [NSString stringWithFormat:#"%f", locationManager.location.coordinate.longitude];
NSLog(#"lat,lon %#%#",latitude,longitude);
home.name = #"";
home.description = #"";
home.latitude = coordinate.latitude;
home.longitude = coordinate.longitude;
Place* office = [[[Place alloc] init] autorelease];
office.name = #"";
office.description = #"";
office.latitude = 22.0000;
office.longitude = 88.0008;
[mapView showRouteFrom:home to:office];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(IBAction)back:(id)sender{
[self dismissViewControllerAnimated:YES completion:nil];
}
-(IBAction)tfs:(id)sender{
TFSViewController *tfs = [[TFSViewController alloc]initWithNibName:#"TFSViewController" bundle:nil];
[self presentViewController:tfs animated:YES completion:nil];
}
#end

Answer 1

The trouble is you're making the location manager and then expecting it to have a location a few micro seconds later. You should be setting the location manager's delegate and then waiting for it to be called. When LM has a location it will call didUpdateLocation and you can use that to call updateCurrentLabel

Answer 2

You should use delegate method -locationManager:didUpdateLocations: to get the locations. CLLocationManager takes few seconds to establish a GPS connection and determine the current location.
http://developer.apple.com/library/ios/documentation/CoreLocation/Reference/CLLocationManagerDelegate_Protocol/CLLocationManagerDelegate/CLLocationManagerDelegate.html#//apple_ref/occ/intfm/CLLocationManagerDelegate/locationManager:didUpdateLocations:
You could also use CLLocation's horizontalAccuracy property to check the accuracy of the location to determine if you want to use the value or discard it.
http://developer.apple.com/library/ios/#documentation/CoreLocation/Reference/CLLocation_Class/CLLocation/CLLocation.html#//apple_ref/occ/cl/CLLocation