How to find the current location in iPhone?

I have written the following code to find the current location. It works well and prints the current location when I print lat2 and logg2 below in NSLOg, but it is not ass开发者_运维问答igning value to lables. When I print label the value is null.

And I want to access lat2 and logg2 values outside the method didUpdateToLocation. I am not able to access these values outside the didUpdateToLocation method even though I have declared logg2 and lat2 globally. Outside this method it gives null value. How can I do that? What is problem here? Is there any sample code or tutorial fot that?

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization.
    }
    return self;
}

-(void)awakeFromNib {
    [self update];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    if (wasFound) return;
    wasFound = YES;

    CLLocationCoordinate2D loc = [newLocation coordinate];

    lat2 = [NSString stringWithFormat: @"%f", loc.latitude];
    logg2= [NSString stringWithFormat: @"%f", loc.longitude];
    NSLog(@"latitude is %@",lat2);
    NSLog(@"longitude is  %@",logg2);
    NSLog(@"*******This is the login view controller did update locationmethod of loginview controller.");
    NSLog(@"latitude is %f",[lat2 floatValue]);
    NSLog(@"longitude  is %f",[logg2 floatValue]);
    labellat.text = [NSString stringWithFormat: @"%f", loc.latitude];
    labellog.text= [NSString stringWithFormat: @"%f", loc.longitude];
    //NSLog(@"text of label is %@",labellat.text);
    //NSLog(@"text of label is %@",labellog.text);

    //lat=loc.latitude;
    //log=loc.longitude;
    //altitude.text = [NSString stringWithFormat: @"%f", newLocation.altitude];

    //    NSString *mapUrl = [NSString stringWithFormat: @"http://maps.google.com/maps?q=%f,%f", loc.latitude, loc.longitude];
    //    NSURL *url = [NSURL URLWithString:mapUrl];
    //    [[UIApplication sharedApplication] openURL:url];
}

- (IBAction)update {
    locmanager = [[CLLocationManager alloc] init];
    [locmanager setDelegate:self];
    [locmanager setDesiredAccuracy:kCLLocationAccuracyBest];
    NSLog(@"*********This is the location update method of login view controller.");
    [locmanager startUpdatingLocation];
}

---

Basic memory management:

lat2 = [NSString stringWithFormat: @"%f", loc.latitude];
logg2= [NSString stringWithFormat: @"%f", loc.longitude];

These strings are destroyed (deallocated) almost right after you create them. Read up on memory management guidelines. Don't use globals either. If you must, this should fix your strings disappearing:

[lat2 release];
[logg2 release];
lat2 = [[NSString stringWithFormat: @"%f", loc.latitude] retain]; // keep string alive until we release it
logg2= [[NSString stringWithFormat: @"%f", loc.longitude] retain];

Oh, and did you remember to connect the outlets to your labels in Interface Builder?

---

Use this to show your latitude and longitude in labels.

labellat.text = [NSString stringWithFormat: @"%.6f", loc.latitude];

labellog.text= [NSString stringWithFormat: @"%.6f", loc.longitude];

Please retain the location coordinate to get the values if you want call this from any other places, otherwise it may autorelase.

---

You can make use of

labellat.text = [NSString stringWithFormat: @"%@", lat2];
labellog.text= [NSString stringWithFormat: @"%@", logg2];

But I think it's better to store the latitude and longitude values as a float itself in an instance variable and thereby getting access to it easily. If you want to show it in a label, use the method stringWithFormat: just as you did.

UPDATE:

The tutorial Hello There: A CoreLocation Tutorial may help you.