How to load the map with the obtained current location in iphone? - iphone

Question

I am new to iphone development.I am creating a map application.I have toolbar below the mapview with a button on it.On clicking the button it displays as an alert to load the current location.In my button click even i hava given code to find current location
-(IBAction) gosearch : (id) sender{
self.locationManager = [[[CLLocationManager alloc] init] autorelease];
self.locationManager.delegate = self;
[locationManager startUpdatingLocation];
}
For me it is not displaying the alert.What should i do?Please help me out. Thanks.

Answer 1

You need to have your controller class implement protocol CLLocationManagerDeligate. This will mean that it gets notified of errors or when the location is posted (for example – locationManager:didUpdateToLocation:fromLocation:)
Then you can pass on the long/lat and radius of view required to the MapView

Answer 2

Make sure for the alert view it looks like this-
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Current Location" message:#"Show Current Location?" delegate:nil cancelButtonTitle:#"Cancel" otherButtonTitles:#"OK"];
[alert show];
and also
- (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex
{
if (buttonIndex != [alertView cancelButtonIndex])
{
map.showsuserlocation = YES;
}
}

Answer 3

I'm not sure I fully understand your questions but here's what I have done to use the location manager.
First, I declare a class that implements CLLocationManagerDelegate
#interface GPSComponent <CLLocationManagerDelegate> {
CLLocationManager *locationManager;
CLLocation *currentLocation;
}
Then, in the class I have:
- (id) init {
locationManager = [[CLLocationManager alloc] init];
// Provide the best possible accuracy (this is the default; just want to write some code).
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters;
// Must move at least 100 meters to get a new location update (default is get all notifications).
locationManager.distanceFilter = 100;
locationManager.delegate = self;
[locationManager startUpdatingLocation];
}
#pragma mark -
#pragma mark CLLocationManagerDelegate methods
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
// If you are about 400 miles south off the coast of Ghana, we might be ignoring your location information. We apologize.
// This is a lazy way to check for failure (in which case the struct is zeroed out).
if((fabs(newLocation.coordinate.latitude) > 0.001) || (fabs(newLocation.coordinate.longitude) > 0.001)) {
NSLog(#"Got location %f,%f", newLocation.coordinate.latitude, newLocation.coordinate.longitude);
if (currentLocation != nil) {
[currentLocation release];
}
currentLocation = newLocation;
[currentLocation retain];
}
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
NSLog(#"Location Manager error");
}
Then, to display a map with the user's location:
// Pull out the longitude and latitude and invoke google maps
- (IBAction)mapItButtonPressed {
NSString *url = [NSString stringWithFormat: #"http://maps.google.com/maps?q=%f,%f", (float)currentLocation.coordinate.latitude, (float)currentLocation.coordinate.longitude];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:url]];
}