如何仅在按下按钮时更新位置

Question

如何让我的应用程序仅在按下按钮时更新位置？

我有一个名为“REFRESH”的按钮。每次按下此按钮时，我都想向我的用户显示他们的位置。例如，51 Bourke Street, Victoria。

但是，我不想定期更新我的位置。我只想在按下按钮时更新它的位置，以节省电池电量。

你怎么看？我做得对吗？

我有这些课程：

• VoteViewController.h 和 VoteViewController.m
• CoreLocationController.h 和 CoreLocationController.m

这就是我所拥有的：

VoteViewController.h 类

@interface VoteViewController : UIViewController <CoreLocationControllerDelegate> 
{
    CoreLocationController *coreController;
}

- (void)locationUpdate:(CLLocation *)location; 
- (void)locationError:(NSError *)error;
- (void)geoReverseAddress:(MKPlacemark *)placeMark;
- (IBAction)refreshButtonPressed;

VoteViewController.m 类

- (void)viewDidLoad
{
    [super viewDidLoad];
    coreController = [[CoreLocationController alloc] init];
    coreController.delegate = self;
}

- (IBAction)refreshButtonPressed
{
    NSLog(@"Refresh Button pressed");
    label.text = [NSString stringWithString:@""];
    [coreController.locationManager startUpdatingLocation];
}

- (void)locationUpdate:(CLLocation *)location 
{
    comments.text = [location description];
    [coreController.locationManager stopUpdatingLocation];
}

- (void)locationError:(NSError *)error 
{
    comments.text = [error description];
    [coreController.locationManager stopUpdatingLocation];
}

- (void)geoReverseAddress:(MKPlacemark *)placeMark
{
    label.text = [NSString stringWithFormat:@"%@ %@, %@", [placeMark subThoroughfare], 
[placeMark thoroughfare], [placeMark locality]]; 
}

CoreLocationController.h 类

@protocol CoreLocationControllerDelegate <NSObject>

@required
- (void)locationUpdate:(CLLocation *)location;
- (void)locationError:(NSError *)error;
- (void)geoReverseAddress:(MKPlacemark *)placeMark;

@end

@interface CoreLocationController : NSObject <CLLocationManagerDelegate, MKReverseGeocoderDelegate>
{
    CLLocationManager *locationManager;
    id delegate;

    MKReverseGeocoder *reverse;
}

@property(nonatomic, retain) CLLocationManager *locationManager;
@property(nonatomic, retain) id delegate;
@end

CoreLocationController.m 类

-(id) init
{
    self = [super init];

    if (self != nil)
    {
        self.locationManager = [[[CLLocationManager alloc] init] autorelease];
        self.locationManager.delegate = self;
        self.locationManager.distanceFilter = kCLHeadingFilterNone;
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    }
    return self;
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
    NSLog(@"Update location");
    [self.delegate locationUpdate:newLocation];

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

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
    [self.delegate locationError:error];
}

- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFailWithError:(NSError *)error
{
    [self.delegate locationError:error];
    [reverse cancel];
    [reverse release];
}

- (void)reverseGeocoder:(MKReverseGeocoder *)geocoder didFindPlacemark:(MKPlacemark *)placemark
{
    [self.delegate geoReverseAddress:placemark];
    [reverse cancel];
    [reverse release];
}

Answer 1

当您第一次启动 CLLocationManager 时，您很可能会从上次运行时获得一个陈旧的位置。一旦解决了这个问题，您将开始获得非常不准确的位置，而设备使用 WiFi 嗅探和小区三角测量，而 GPS 正在寻找解决方案。

因此，在您的 didUpdateToLocation 方法中，您可能希望丢弃第一个命中，然后测试您的 newLocation 对象的 .horizo​​ntalAccuracy 值以获得足够低的值以供信任。

除此之外，我看不出你发来的东西有什么不好的地方。我不确定我是否会麻烦将位置获取工作包装在它自己的类中，我可能只是在我的 viewController 中做到这一点。但这是一种风格选择。如果您要在其他地方重用此功能，那么您所拥有的显然是可行的方法。