使用CLLocationManager和MKReverseGeocoder获取城市名称

Question

我正在尝试使用MKReverseGeoCoder获取用户当前所在城市的名称，但它有一些我无法识别的错误。以下是详细信息：

它有一些我无法识别的错误

Undefined symbols:
  ".objc_class_name_CLLocationManager", referenced from:
      literal-pointer@__OBJC@__cls_refs@CLLocationManager in mapViewController.o
  "_kCLLocationAccuracyNearestTenMeters", referenced from:
      _kCLLocationAccuracyNearestTenMeters$non_lazy_ptr in mapViewController.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

下面是我的代码：

mapViewController.m

//
//  mapViewController.m
//  map
//
//  Created by Ashutosh Tiwari on 7/23/10.
//  Copyright ISU 2010. All rights reserved.
//
#import <MapKit/MapKit.h>
#import "mapViewController.h"

@implementation mapViewController


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    CLLocationManager *locationManager = [[[CLLocationManager alloc] init] autorelease];
    locationManager.delegate = self;
    locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
    [locationManager startUpdatingLocation];

    [super viewDidLoad];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation 
{

    MKReverseGeocoder *geoCoder = [[MKReverseGeocoder alloc] initWithCoordinate:newLocation.coordinate];
    geoCoder.delegate = self;
    [geoCoder start];
}

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

- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFindPlacemark:(MKPlacemark *)placemark
{
    MKPlacemark * myPlacemark = placemark;

    NSString *kABPersonAddressCityKey;
    NSString *city = [myPlacemark.addressDictionary objectForKey:(NSString*) kABPersonAddressCityKey];
}

- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFailWithError:(NSError *)error
{
    NSLog(@"reverseGeocoder:%@ didFailWithError:%@", geocoder, error);
}

- (void)dealloc {
    [super dealloc];
}

@end

Answer 1

添加链接到项目的CoreLocation.framework (目标设置/链接库/添加/选择CoreLocation.framework)

添加：简要说明每个方法的作用：

• viewDidLoad:

创建位置实例并开始更新位置-以获取当前用户coordinates

• locationManager:didUpdateToLocation:

当CLLocationManager接收到用户坐标时调用。现在，我们可以将它们传递给MKReverseGeocoder以获取用户位置的信息(国家、城市etc)

• locationManager:didFailWithError:和reverseGeocoder:didFailWithError:

处理可能的错误-只需将它们记录在当前implementation

• reverseGeocoder:didFindPlacemark:中

当MKReverseGeocoder找到坐标的信息时调用，您可以从获取的MKPlacemark实例的相应字段中检索所需的信息。

kABPersonAddressCityKey -是placemark地址字典中城市字段的关键字符串。它在ABPerson.h报头中定义，因为placemark和ABRecord地址的地址字段是相同的。因此，要使用该密钥，您可能还需要链接到AddressBook框架。