Current location query on click event - iphone

Question

I am Showing Australia continent when my Map application launch. I have one button on which I want to set coding for current location and zoom in to that location after pressing butoon. I am getting current latitude & longitude and able to pass in Web-service url. I did following coding
- (void)viewDidLoad
{
//to set the australia region
CLLocationCoordinate2D AusLoc = {-19.048230,133.685730};
MKCoordinateSpan AusSpan = MKCoordinateSpanMake(45, 45);
MKCoordinateRegion AusRegion = MKCoordinateRegionMake(AusLoc, AusSpan);
mapView.region = AusRegion;
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; // 100 m
[locationManager startUpdatingLocation]; }
and
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
{
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];
}
NSString *lati=[NSString stringWithFormat:#"%f", newLocation.coordinate.latitude];
NSString *longi=[NSString stringWithFormat:#"%f", newLocation.coordinate.longitude];
}
on Search button(web service calling)
NSString *url = [NSString stringWithFormat:#"http://.....url...../hespdirectory/phpsqlsearch_genxml.php?lat=%f&lng=%f&radius=%f",locationManager.location.coordinate.latitude,locationManager.location.coordinate.longitude,radius];
Updated with coding:
- (IBAction) showAddress {
if (locationManager.location == nil)
{
NSLog(#"user location not found yet or service disabled/denied");
}
else
{
// Change map region using span (degrees)...
MKCoordinateSpan span = MKCoordinateSpanMake(0.001, 0.001);
MKCoordinateRegion region = MKCoordinateRegionMake
(locationManager.location.coordinate, span);
[mapView setRegion:region animated:YES];
}
}
When I set mapView.showUserLocation = YES; it shows current location when map application launch that is before tapping button. I am confused with previous answer. So What code should I put under button click event to show current location and also suggest If there is any change to pass current Lati and longi in web service url after giving coding for click event. Thanks in advance
Edited:-
- (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>) annotation
{
MKPinAnnotationView *annView=[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:#""];
annView.pinColor = MKPinAnnotationColorGreen;
//annView.animatesDrop=TRUE;
annView.canShowCallout = YES;
annView.calloutOffset = CGPointMake(-5, 5);
annView.enabled = YES;
annView.image = [UIImage imageNamed:#"flagg.png"];
UIButton* rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
[rightButton addTarget:self
action:#selector(showDetails:)
forControlEvents:UIControlEventTouchUpInside];
annView.rightCalloutAccessoryView = rightButton;
NSLog(#"Created annotation at: %f %f", ((CustomPlacemark*)annotation).coordinate.latitude, ((CustomPlacemark*)annotation).coordinate.longitude);
[annView addObserver:self
forKeyPath:#"selected"
options:NSKeyValueObservingOptionNew
context:#"GMAP_ANNOTATION_SELECTED"];
[annView autorelease];
return annView;
}
//return nil;
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context{
NSString *action = (NSString*)context;
// We only want to zoom to location when the annotation is actaully selected. This will trigger also for when it's deselected
if([[change valueForKey:#"new"] intValue] == 1 && [action isEqualToString:#"GMAP_ANNOTATION_SELECTED"])
{
if([((MKAnnotationView*) object).annotation isKindOfClass:[CustomPlacemark class]])
{
CustomPlacemark *place = ((MKAnnotationView*) object).annotation;
// Zoom into the location
[mapView setRegion:place.coordinateRegion animated:TRUE];
NSLog(#"annotation selected: %f %f", ((MKAnnotationView*) object).annotation.coordinate.latitude, ((MKAnnotationView*) object).annotation.coordinate.longitude);
}
}
}
In Search button(calling webservice)
CLLocationCoordinate2D location;
//currentLocation = newLocation;
float radius = [[arrayNo objectAtIndex:[pickerView selectedRowInComponent:0]] floatValue];
//NSURL *url = [[NSURL alloc] initWithString:#"http://www.hettich.com.au/hespdirectory/phpsqlsearch_genxml.php?lat=-33.853468&lng=150.94042160000004&radius=5"];
NSString *url = [NSString stringWithFormat:#"http://www.hettich.com.au/hespdirectory/phpsqlsearch_genxml.php?lat=%f&lng=%f&radius=%f",locationManager.location.coordinate.latitude,locationManager.location.coordinate.longitude,radius];
//NSLog(#"NSString *url");
NSLog(#"%#", url);
NSURL *URL = [NSURL URLWithString:url];
NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithContentsOfURL:URL];
//Initialize the delegate.
XMLParser *parser = [[XMLParser alloc] initXMLParser];
//Set delegate
[xmlParser setDelegate:parser];
//Start parsing the XML file.
BOOL success = [xmlParser parse];
if(success)
{ resultButton.userInteractionEnabled = YES;
// NSMutableArray* annotations = [[NSMutableArray alloc] init];
for (int i = 0; i < [appDelegate.markers count]; i++)
{
marker *aMarker = [appDelegate.markers objectAtIndex:i];
location.latitude = [aMarker.lat floatValue];
location.longitude =[aMarker.lng floatValue];
AddressAnnotation *annob = [[AddressAnnotation alloc] initWithCoordinate:location];
annob.title = aMarker.name;
annob.subTitle = aMarker.address;
[mapView addAnnotation:annob];
[annob release];
CLLocationCoordinate2D ausLoc = {location.latitude,location.longitude}; //for zoom in the showroom results region
MKCoordinateSpan ausSpan = MKCoordinateSpanMake(0.108889, 0.169922);
MKCoordinateRegion ausRegion = MKCoordinateRegionMake(ausLoc, ausSpan);
NSLog(#"No Errors");
mapView.region = ausRegion;
}
}

Answer 1

In your button tapped method, you should first check if the location manager has obtained a location and then set the map's center or region to the user's location:
if (locationManager.location == nil)
{
NSLog(#"user location not found yet or service disabled/denied");
}
else
{
// Change map center (preserving current zoom level)...
[mapView setCenterCoordinate:locationManager.location.coordinate animated:YES];
// --OR--
// Change map region using distance (meters)...
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance
(locationManager.location.coordinate, 1000, 1000);
[mapView setRegion:region animated:YES];
// --OR--
// Change map region using span (degrees)...
MKCoordinateSpan span = MKCoordinateSpanMake(0.001, 0.001);
MKCoordinateRegion region = MKCoordinateRegionMake
(locationManager.location.coordinate, span);
[mapView setRegion:region animated:YES];
}
In the didUpdateToLocation method, you are setting a "currentLocation" variable but I don't see a need for it. The locationManager already has a location property.
In any case, only considering absolute latitudes or longitudes greater than 0.001 as "valid" is incorrect because a) it excludes locations near the equator or prime meridian (even though you're only interested in Australia this logic is the wrong way to go), and b) it's better instead to check if newLocation itself is nil.