CLLocation返回负速度

Question

我正在开始一个使用coreLocation和mapkit框架的新应用程序.

我的问题是试图让当前的速度总是给我一个负值,我把我的iPhone带到一个有3g信号的地方并没关系,location.speed值总是-1.

这是重要的代码:

#define kRequiredAccuracy 1500.0 //meters
#define kMaxAge 60.0 //seconds

在init方法中:

self.locationManager=[[CLLocationManager alloc] init];
self.locationManager.delegate=self;
self.locationManager.desiredAccuracy=kCLLocationAccuracyNearestTenMeters;

然后didUpdateToLocation:

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

    NSTimeInterval ageInSeconds = [newLocation.timestamp timeIntervalSinceNow];
    NSLog(@"Location: %@", [newLocation description]);

    if( newLocation.horizontalAccuracy > kRequiredAccuracy || fabs(ageInSeconds) > kMaxAge )
    {
        NSLog(@"inacurate position");
        [self.delegate inacuratePosition];

    }
    else {

    [self.delegate locationUpdate:newLocation andOldLocation:oldLocation];
    location=newLocation.coordinate;


    }


    if(tracking)
    {   
    [self updatePosition];
    }
    if(firstTime)
    {
        [self placeStartMark];
        firstTime=FALSE;
    }



}

最后在我正在实现协议的视图控制器中:

- (void)locationUpdate:(CLLocation *)newLocation andOldLocation:(CLLocation*)oldLocation{

    double speed = [newLocation speed] *3.6;



    double altitude= [newLocation altitude];
    [self checkMaxSpeedAndAltitude:speed :altitude];
    if(speed< 0)
        speed=0;



    locationLabel.text=[NSString stringWithFormat:@"speed: %f km/h   altitude: %f m", speed,altitude];
}

我变得疯狂,所以如果有人知道任何解决方案,它肯定会有所帮助.谢谢

Answer 1

通常,如果使用的位置检测机制不支持它,您将获得负高度和速度.例如,当使用Wi-Fi或小区三角测量时.你确定,你正在获得GPS更新,所以你在自由天空下进行测试吗？即使这样,您仍然会收到WiFi和手机信号塔位置更新,因此您需要将其过滤掉.

Wi-Fi位置更新通常为65米水平精度.