使用 MKMapView 时如何设置精度和距离过滤器

Question

当我使用setShowsUserLocation 和MKMapView 来跟踪用户位置时，如何设置精度和距离过滤器？我不是在说CLLocationManager。

谢谢，

Answer 1

您无法控制内部MKMapView 位置管理器（用于跟踪带有蓝点的用户）的准确性，但您可以创建自己的位置管理器并使用它来重新定位地图。这是一个食谱...

处理核心位置权限

在核心位置委托中：

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
    if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusDenied){
        NSLog(@"User has denied location services");
    } else {
        NSLog(@"Location manager did fail with error: %@", error.localizedFailureReason);
    }
}

就在设置位置管理器之前：

if (![CLLocationManager locationServicesEnabled]){
    NSLog(@"location services are disabled"];
    return;
}
if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusDenied){
    NSLog(@"location services are blocked by the user");
    return;
}
if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusAuthorized){
    NSLog(@"location services are enabled");
}  
if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusNotDetermined){
    NSLog(@"about to show a dialog requesting permission");
}

设置核心位置

self.locationManager = [CLLocationManager new];
self.locationManager.purpose = @"Tracking your movements on the map.";
self.locationManager.delegate = self;

/* Pinpoint our location with the following accuracy:
 *
 *     kCLLocationAccuracyBestForNavigation  highest + sensor data
 *     kCLLocationAccuracyBest               highest     
 *     kCLLocationAccuracyNearestTenMeters   10 meters   
 *     kCLLocationAccuracyHundredMeters      100 meters
 *     kCLLocationAccuracyKilometer          1000 meters 
 *     kCLLocationAccuracyThreeKilometers    3000 meters
 */
self.locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;

/* Notify changes when device has moved x meters.
 * Default value is kCLDistanceFilterNone: all movements are reported.
 */
self.locationManager.distanceFilter = 10.0f;

/* Notify heading changes when heading is > 5.
 * Default value is kCLHeadingFilterNone: all movements are reported.
 */
self.locationManager.headingFilter = 5;

// update location
if ([CLLocationManager locationServicesEnabled]){
    [self.locationManager startUpdatingLocation];
}

使用我们的位置管理器重新定位地图

- (void)locationManager:(CLLocationManager *)manager 
    didUpdateToLocation:(CLLocation *)newLocation 
           fromLocation:(CLLocation *)oldLocation 
{
    MKCoordinateRegion region = { { 0.0f, 0.0f }, { 0.0f, 0.0f } };
    region.center = newLocation.coordinate;
    region.span.longitudeDelta = 0.15f; 
    region.span.latitudeDelta = 0.15f;
    [self.mapView setRegion:region animated:YES];
}

把它放在委托人身上。 MKMapView 没有距离或精度过滤器，只有 CLLocationManager 有。 MKMapView 是围绕一个点的区域跨度，在上面的示例中为 0.15 度（0.15*111 公里）。

我尝试过但没有成功的方法

文档没有说明MKMapView 从哪里获取更新。我试过了

- (void)locationManager:(CLLocationManager *)manager 
    didUpdateToLocation:(CLLocation *)newLocation 
           fromLocation:(CLLocation *)oldLocation {
    NSLog(@"newLocation %@", newLocation.timestamp);
    NSLog(@"last map location %@", [NSString stringWithFormat:@"%@",[[[self.mapView userLocation] location] timestamp]]);
}

我得到了不同的价值观。看起来MKMapView 使用了自己的CLLocationManager，这意味着您无法设置其准确性。您也不能为MKMapView 的CLLocationManager 添加您的代表。

我的印象是，设置准确性的唯一方法是将显示用户位置设置为 NO 并创建一个带有蓝点的自定义注释，这意味着手动重新定位已发布的地图。您可以使用 github 项目 artifact-extractor 从 SDK 中获取蓝点图形。

我不知道我是否遗漏了什么，或者MKMapView 的这一部分很糟糕。

Answer 2

这里显示地图是一个示例代码。

首先在您的 .h 文件中导入 MKMapKit 和 CoreLocation 框架。

#import <MapKit/MapKit.h>
 #import <CoreLocation/CoreLocation.h>

在 .h 文件中添加 MKMapKit 和 CoreLocation 委托

@interface MapViewController : UIViewController <MKMapViewDelegate, CLLocationManagerDelegate>


CGPoint gameMapCenter = CGPointMake([[UIScreen mainScreen] bounds].size.width / 2, [[UIScreen mainScreen] bounds].size.height / 2);
    gameMapView = [[MKMapView alloc] initWithFrame:CGRectMake(0, 0, 640, 620)];
    [gameMapView setCenter:gameMapCenter];
    [gameMapView setMapType:MKMapTypeStandard];
    [gameMapView setDelegate:self];
    [self.view addSubview:gameMapView];
    [gameMapView setShowsUserLocation:YES];

使用CLLocationManager 获取用户位置。

声明一个 CLLocationManager 的实例

CLLocationManager *locationManager;

在ViewDidLoad

locationManager = [[CLLocationManager alloc] init];

[locationManager setDelegate:self];

[locationManager setDesiredAccuracy:kCLLocationAccuracyBest];

[locationManager setDistanceFilter:kCLDistanceFilterNone];

[locationManger startUpdatingLocation];

startUpdatingLocation方法实现：

(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation 
{
      //Your Stuff
}

Answer 3

您无法设置准确度，但是，您可以通过 MKMapView 委托方法中的 userLocation 获取准确度。

- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation
{
    NSLog(@"%f", userLocation.location.horizontalAccuracy);
}