Trouble finding location with iPhone in urban environments - iphone

Question

We are developing an iPhone app and need to know the user's approximate location. We are using CoreLocation. We can do it ok in suburban environments, but in New York City - we're not able to get any longitude/latitude info.
We suspect it's cos GPS signals are weak among highrises... But shouldn't we still be able to get some approximate location info back?
Any ideas on what may cause/fix this? Thanks.
#import "RootViewController.h"
#import "SlickEatsAppDelegate.h"
#import "SlickEatsWelcomePage.h"
#import "XMLParserShowTodaysOffer.h"
#import "SlickEatsSplashScreen.h"
#implementation RootViewController
#synthesize locationManager,currentLocation,appDelegate;
#synthesize getStartedButton,splashLogoImageView,howItWorkImageView,workButton,infoView;
#synthesize xmlParserShowTodaysOffer;//activityIndicator
#pragma mark -
#pragma mark View lifecycle
- (void)viewDidLoad {
[super viewDidLoad];
[self connectedToNetwork];
self.navigationController.navigationBar.hidden = TRUE;
if(locationManager == nil)
{
[[self locationManager] startUpdatingLocation];
}
//[self.view addSubview:SlickEatsView];
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem;
}
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
}
/*-(IBAction)getStartedButton_Clicked:(id)sender
{
activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
self.activityIndicator.frame = CGRectMake(135, 150, 40, 40);
[self.view addSubview:activityIndicator];
if (self.activityIndicator.isAnimating == NO)
{
[self.activityIndicator startAnimating];
}
/*if(locationManager == nil)
{
[[self locationManager] startUpdatingLocation];
}*/
/*SlickEatsWelcomePage *welcomePage = [[SlickEatsWelcomePage alloc]initWithNibName:#"SlickEatsWelcomePage" bundle:nil];
appDelegate = (SlickEatsAppDelegate *)[[UIApplication sharedApplication]delegate];
xmlParserShowTodaysOffer = [XMLParserShowTodaysOffer alloc];
xmlParserShowTodaysOffer.currentCity = appDelegate.myCurrentCity;
xmlParserShowTodaysOffer.currentLatitude = appDelegate.myCurrentLatitude;
xmlParserShowTodaysOffer.currentLongitude = appDelegate.myCurrentLongitude;
[xmlParserShowTodaysOffer initXMLParser];
[xmlParserShowTodaysOffer release];
[self.navigationController pushViewController:welcomePage animated:YES];
[welcomePage release];
[activityIndicator removeFromSuperview];
//[[UIApplication sharedApplication] openURL:[NSURL URLWithString:#"9763912503"]];
}*/
- (CLLocationManager *)locationManager {
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move
locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters; // 100 m
[locationManager startUpdatingLocation];
return locationManager;
}
#pragma mark -
#pragma mark CLLocationManagerDelegate Methods
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation {
appDelegate = (SlickEatsAppDelegate *)[[UIApplication sharedApplication]delegate];
int degrees = newLocation.coordinate.latitude;
double decimal = fabs(newLocation.coordinate.latitude - degrees);
int minutes = decimal * 60;
double seconds = decimal * 3600 - minutes * 60;
NSString *lat = [NSString stringWithFormat:#"%d° %d' %1.4f\"",
degrees, minutes, seconds];
//latLabel.text = lat;
NSLog(#"Current..Latitude::%#",lat);
NSString *CurrentLatitude = [NSString stringWithFormat:#"%lf",newLocation.coordinate.latitude];
NSLog(#"Current..Latitude::%#",CurrentLatitude);
//self.myCurrentLatitude=lat;
degrees = newLocation.coordinate.longitude;
decimal = fabs(newLocation.coordinate.longitude - degrees);
minutes = decimal * 60;
seconds = decimal * 3600 - minutes * 60;
NSString *longt = [NSString stringWithFormat:#"%d° %d' %1.4f\"", degrees, minutes, seconds];
//longLabel.text = longt;
NSLog(#"Current..Longitude::%#",longt);
NSString *CurrentLongitude = [NSString stringWithFormat:#"%lf",newLocation.coordinate.longitude];
NSLog(#"Current..Longitude::%#",CurrentLongitude);
appDelegate.myCurrentLatitude = CurrentLatitude;
appDelegate.myCurrentLongitude = CurrentLongitude;
MKReverseGeocoder *geoCoder = [[MKReverseGeocoder alloc] initWithCoordinate:newLocation.coordinate];
geoCoder.delegate = self;
[geoCoder start];
}
// this delegate is called when the reverseGeocoder finds a placemark
- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFindPlacemark:(MKPlacemark *)placemark
{
MKPlacemark * myPlacemark = placemark;
// with the placemark you can now retrieve the city name
NSString *city =[ myPlacemark.addressDictionary objectForKey:(NSString*) kABPersonAddressCityKey];
// NSString *city = (NSString *)[myPlacemark.locality length];
NSLog(#"Current Add::%#",city);
appDelegate.myCurrentCity = city;
//[self sendLocation];
}
// this delegate is called when the reversegeocoder fails to find a placemark
- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFailWithError:(NSError *)error
{
NSLog(#"reverseGeocoder:%# didFailWithError:%#", geocoder, error);
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
NSLog(#"error%#",error);
switch([error code])
{
case kCLErrorNetwork: // general, network-related error
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error" message:#"please check your network connection or that you are not in airplane mode" delegate:self cancelButtonTitle:#"Ok" otherButtonTitles:nil, nil];
[alert show];
[alert release];
}
break;
case kCLErrorDenied:{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error" message:#"user has denied to use current Location " delegate:self cancelButtonTitle:#"Ok" otherButtonTitles:nil, nil];
[alert show];
[alert release];
}
break;
default:
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error" message:#"unknown network error" delegate:self cancelButtonTitle:#"Ok" otherButtonTitles:nil, nil];
[alert show];
[alert release];
}
break;
}
}
-(void)sendLocation
{
NSLog(#"in Send Location..");
SlickEatsWelcomePage *welcomePage = [[SlickEatsWelcomePage alloc]initWithNibName:#"SlickEatsWelcomePage" bundle:nil];
appDelegate = (SlickEatsAppDelegate *)[[UIApplication sharedApplication]delegate];
xmlParserShowTodaysOffer = [XMLParserShowTodaysOffer alloc];
xmlParserShowTodaysOffer.currentCity = appDelegate.myCurrentCity;
xmlParserShowTodaysOffer.currentLatitude = appDelegate.myCurrentLatitude;
xmlParserShowTodaysOffer.currentLongitude = appDelegate.myCurrentLongitude;
[xmlParserShowTodaysOffer initXMLParser];
[xmlParserShowTodaysOffer release];
[self.navigationController pushViewController:welcomePage animated:YES];
[welcomePage release];
//[locationManager release];
}
-(IBAction)workButton_clicked:(id)sender
{
/*activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
self.activityIndicator.frame = CGRectMake(135, 150, 40, 40);
[self.splashLogoImageView addSubview:activityIndicator];
if (self.activityIndicator.isAnimating == NO)
{
[self.activityIndicator startAnimating];
}*/
SlickEatsSplashScreen *intro = [[SlickEatsSplashScreen alloc]initWithNibName:#"SlickEatsSplashScreen" bundle:nil];
[self.navigationController pushViewController:intro animated:YES];
[intro release];
//[activityIndicator removeFromSuperview];
}
- (void)connectedToNetwork {
BOOL aflag= ([NSString stringWithContentsOfURL:[NSURL URLWithString:#"http://www.google.co.in/"]]!=NULL)?YES:NO;
if (!aflag) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:#"Sorry!....You are not connected to network "
delegate:self cancelButtonTitle:#"Exit" otherButtonTitles:nil];
[alert show];
[alert release];
}
}
/*
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
}
*/
/*
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
}
*/
/*
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
}
*/
/*
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations.
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
*/
/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
// Return NO if you do not want the specified item to be editable.
return YES;
}
*/
/*
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the row from the data source.
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
}
}
*/
/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
}
*/
/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath {
// Return NO if you do not want the item to be re-orderable.
return YES;
}
*/
#pragma mark -
#pragma mark Memory management
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Relinquish ownership any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
// Relinquish ownership of anything that can be recreated in viewDidLoad or on demand.
// For example: self.myOutlet = nil;
}
- (void)dealloc {
[super dealloc];
[workButton release];
[howItWorkImageView release];
[splashLogoImageView release];
[getStartedButton release];
[locationManager release];
}
#end

Answer 1

I suspect that you are requesting GPS-like accuracy when the GPS chip isn't getting any signals due to the high rise buildings:
locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters; // 100 m
Try commenting out the above statement and test it out in the field -- see how accurate the coordinates that you get.

Answer 2

Do you have a data connection? I've heard that it's sometimes tough to get a connection at all in Manhattan on certain networks, due to both the buildings and an overloaded network. If you're not getting data, it's going to be tough to get a fix.