Reverse Geocoding
You’ll begin the process of implementing reverse geocoding by adding a new instance variable to MapController.m to store a reference to the CLGeocoder object. You do all this by adding the bolded code in Listing 18-1 to MapController.m. As you’ll see later, you’ll need that reference to cancel a request.
Listing 18-1: Updating the MapController Implementation
#import “MapController.h”
#import “RTAppDelegate.h”
#import “Trip.h”
@interface MapController () {
CLGeocoder* geocoder;
}
@end
Next, you allocate and initialize the CLGeocoder and send it a message to return the information for the current location. Adding the bolded code in Listing 18-2 to goToLocation in MapController.m does that for you.
Listing 18-2: Updating goToLocation
- (void)goToLocation:(id)sender {
void (^clGeocodeCompletionHandler)(NSArray *, NSError *) =
^(NSArray *placemarks, NSError *error){
CLPlacemark *placemark = [placemarks objectAtIndex:0];
if (error!= nil || placemark == nil) {
NSLog(@”Geocoder failure! Error code: %u,
description: %@, and reason: %@”, error.code, [error localizedDescription],
[error localizedFailureReason]);
}
else {
mapView.userLocation.subtitle =
[NSString stringWithFormat: @” lat:%f lon:%f”, placemark.location.coordinate.latitude,
placemark.location.coordinate.longitude];
if ([placemark.areasOfInterest objectAtIndex:0]) {
mapView.userLocation.title =
[placemark.areasOfInterest objectAtIndex:0];
}
else {
if (placemark.thoroughfare) ...
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