地理编码与反地理编码

            地理编码是把某个具体的位置计算为经纬度，反地理编码正好相反。

            效果：通过输入框的搜索，也能定位到具体的位置。长按地图，就能获得某个位置的详细地址。

 #import "ViewController.h"
 #import

 @interface ViewController ()

 @property (nonatomic, strong) MKMapView * mapView;
 @property (nonatomic, strong) CLLocationManager * locationManager;
 @property (nonatomic, strong) UITextField * textField;
 @property (nonatomic, strong) NSString * titleString;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];

 //    116.456011,39.941272
     _mapView = [[MKMapView alloc] initWithFrame:self.view.bounds];
     [_mapView setDelegate:self];
     [_mapView setShowsUserLocation:YES];
     [_mapView setMapType:MKMapTypeStandard];
     [self.view addSubview:_mapView];

     UILongPressGestureRecognizer * longpressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressed:)];
     [_mapView addGestureRecognizer:longpressGestureRecognizer];

     _textField = [[UITextField alloc] init];
     [_textField setTranslatesAutoresizingMaskIntoConstraints:NO];
     [_textField setBackgroundColor:[UIColor whiteColor]];
     [self.view addSubview:_textField];

     UIButton * btn = [UIButton buttonWithType:UIButtonTypeCustom];
     [btn setBackgroundColor:[UIColor orangeColor]];
     [btn setTitle:@"查找" forState:UIControlStateNormal];
     [btn setTranslatesAutoresizingMaskIntoConstraints:NO];
     [btn addTarget:self action:@selector(theBtnPressed:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:btn];

     [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-20-[_textField][btn(100)]-20-|"
                                                                      options:0
                                                                      metrics:nil
                                                                         views:NSDictionaryOfVariableBindings(_textField,btn)]];
     [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[_textField(30)]-(-30)-[btn(30)]"
                                                                       options:0
                                                                       metrics:nil
                                                                         views:NSDictionaryOfVariableBindings(_textField,btn)]];

     //检测定位功能是否开启
     if([CLLocationManager locationServicesEnabled]){

         if(!_locationManager){

             _locationManager = [[CLLocationManager alloc] init];

             if([_locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)]){
                 [_locationManager requestWhenInUseAuthorization];
                 [_locationManager requestAlwaysAuthorization];

             }

             //设置代理
             [_locationManager setDelegate:self];
             //设置定位精度
             [_locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
             //设置距离筛选
             [_locationManager setDistanceFilter:100];
             //开始定位
             [_locationManager startUpdatingLocation];
             //设置开始识别方向
             [_locationManager startUpdatingHeading];

         }

     }else{
         UIAlertView * alertView = [[UIAlertView alloc] initWithTitle:nil
                                                              message:@"您没有开启定位功能"
                                                             delegate:nil
                                                    cancelButtonTitle:@"确定"
                                                    otherButtonTitles:nil, nil nil];
         [alertView show];
     }
 }

 //点击按钮执行此方法
 - (void)theBtnPressed:(id)sender {
     [_textField resignFirstResponder];
     if([_textField.text length] == 0){

         return;
     }
     [self geocoder:_textField.text];
 }

 #pragma mark LongPress
 - (void)longPressed:(UILongPressGestureRecognizer *)recognizer {
     if(recognizer.state == UIGestureRecognizerStateBegan){
         CGPoint point = [recognizer locationInView:_mapView];
         CLLocationCoordinate2D coordinate2D = [_mapView convertPoint:point toCoordinateFromView:_mapView];

         [_mapView removeAnnotations:_mapView.annotations];

         CLLocation * location = [[CLLocation alloc] initWithLatitude:coordinate2D.latitude longitude:coordinate2D.longitude];

         [self reverseGeocoder:location];

 //        MKPointAnnotation * pointAnnotation = [[MKPointAnnotation alloc] init];
 //        [pointAnnotation setTitle:_titleString];
 //        [pointAnnotation setCoordinate:coordinate2D];
 //        [_mapView addAnnotation:pointAnnotation];
     }
 }

 //授权状态发生改变的时候执行
 - (void)locationManager:(CLLocationManager *)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status {
     switch(status){
         case kCLAuthorizationStatusDenied:
         {
             UIAlertView * alertView = [[UIAlertView alloc] initWithTitle:nil
                                                                  message:@"定位功能没有开启" delegate:nil
                                                        cancelButtonTitle:@"确定" otherButtonTitles:nil, nil nil];
             [alertView show];
         }
             break;
         default:
             break;
     }
 }

 #pragma mark mapViewDelegate
 - (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id)annotation{
     static NSString * key = @"key";
     MKPinAnnotationView * pinAnnotationView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:key];

     if(pinAnnotationView == nil){
         pinAnnotationView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:key];
         [pinAnnotationView setCanShowCallout:YES];
     }

     if([annotation isKindOfClass:[MKUserLocation class]]){
         [pinAnnotationView setPinColor:MKPinAnnotationColorRed];
         [((MKUserLocation *)annotation) setTitle:_titleString];
     }else{
         [pinAnnotationView setPinColor:MKPinAnnotationColorPurple];
     }

     return pinAnnotationView;
 }

 #pragma mark - CLLocationManangerDelegate
 //定位成功以后调用
 - (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations {
     [_locationManager stopUpdatingLocation];
     CLLocation * location = locations.lastObject;

     MKCoordinateRegion coordinateRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude), MKCoordinateSpanMake(0.1, 0.1));

     [_mapView setRegion:[_mapView regionThatFits:coordinateRegion] animated:YES];

 //    [self reverseGeocoder:location];
 }

 - (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
     NSLog(@"error:%@",error);
 }


 #pragma mark Geocoder
 //反地理编码
 - (void)reverseGeocoder:(CLLocation *)currentLocation {

     CLGeocoder * geocoder = [[CLGeocoder alloc] init];
     [geocoder reverseGeocodeLocation:currentLocation completionHandler:^(NSArray *placemarks, NSError *error) {

         if(error || placemarks.count == 0){
             NSLog(@"error");
         }else{

             CLPlacemark * placemark = placemarks.firstObject;

             self.titleString = placemark.name;
             MKPointAnnotation * pointAnnotation = [[MKPointAnnotation alloc] init];
             [pointAnnotation setTitle:placemark.name];
             [pointAnnotation setCoordinate:CLLocationCoordinate2DMake(placemark.location.coordinate.latitude, placemark.location.coordinate.longitude)];
             [_mapView addAnnotation:pointAnnotation];

             NSLog(@"placemark:%@",[[placemark addressDictionary] objectForKey:@"City"]);
         }

     }];
 }

 //地理编码
 - (void)geocoder:(NSString *)str {
     CLGeocoder * geocoder = [[CLGeocoder alloc] init];
     [geocoder geocodeAddressString:str completionHandler:^(NSArray *placemarks, NSError *error) {

         if(error || placemarks.count == 0){
             NSLog(@"error");
         }else{
             CLPlacemark * placemark = placemarks.firstObject;
             MKCoordinateRegion coordinateRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(placemark.location.coordinate.latitude, placemark.location.coordinate.longitude), MKCoordinateSpanMake(0.1, 0.1));

             [_mapView setRegion:[_mapView regionThatFits:coordinateRegion] animated:YES];

             MKPointAnnotation * pointAnnotation = [[MKPointAnnotation alloc] init];
             [pointAnnotation setTitle:placemark.name];
             [pointAnnotation setCoordinate:CLLocationCoordinate2DMake(placemark.location.coordinate.latitude, placemark.location.coordinate.longitude)];
             [_mapView addAnnotation:pointAnnotation];
         }

     }];
 }

 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }

 @end

           参考：http://blog.csdn.net/chenyufeng1991/article/details/48596791