iOS定位服务与地图开发(3)---地理信息编码查询

即根据一个NSString的文字描述对象获取相关的地理坐标。

采用CLGeocoder类操作，具体方法：

1>geocodeAddressDictionary:completionHandler: 通过指定一个地址信息字典对象参数进行查询

2>geocodeAddressString:completionHandler:通过指定一个地址信息字符串参数进行查询

3>geocodeAddressString:inRegion:completionHandler:通过制定地址信息字符串和查询范围进行查询

- (IBAction)geocodeQuery:(id)sender
{NSString *queryStr = nil;// 从界面文本框输入地址字符串if (_textField.text == nil || [_textField.text length] == 0) {return ;}CLGeocoder *geocoder = [[CLGeocoder alloc] init];[geocoder geocodeAddressString:queryStr completionHandler:^(NSArray *placemarks, NSError *error) {NSLog(@"查询记录数:%i",[placemarks count]);if ([placemarks count] > 0) {CLPlacemark *placemark = [placemarks objectAtIndex:0];CLLocationCoordinate2D coordinate = placemark.location.coordinate;// 生成经纬度字符串NSString *strCoordinate = [NSString stringWithFormat:@"经度：%3.5f,纬度：%3.5f",coordinate.latitude,coordinate.longitude];NSDictionary *addressDict = placemark.addressDictionary;NSString *address = [addressDict objectForKey:(NSString *)kABPersonAddressStreetKey];address = address == nil ? @"" : address;NSString *state = [addressDict objectForKey:(NSString *)kABPersonAddressStateKey];state = state == nil ? @"" : state;NSString *city = [addressDict objectForKey:(NSString *)kABPersonAddressCityKey];city = city == nil ? @"" : city;//  获取地标对应的可读的文字信息，一般返回到UI显示NSString *streetInfo = [NSString stringWithFormat:@"%@\n%@\n%@\n%@\n",strCoordinate,state,address,city];}}];
}

使用geocodeAddressString:inRegion:completionHandler:指定查询区域：

 CLRegion *region = [[CLRegion alloc] initCircularRegionWithCenter:_currLocation.coordinate radius:1000.0f identifier:@"GeocodeRegion"];CLGeocoder *geocoder = [[CLGeocoder alloc] init];[geocoder geocodeAddressString:queryStr inRegion:region completionHandler:^(NSArray *placemarks, NSError *error) {.......}];

CLRegion对象封装了一个地理区域类。

构造方法参数：

center：指定区域中心点

radius:指定区域半径，单位为米

identifier:为区域指定一个标识