CLLocation 返回负速度 [英] CLLocation returning negative speed

问题描述

我正在启动一个使用 coreLocation 和 mapkit 框架的新应用程序.

I'm starting a new app which uses the coreLocation and the mapkit frameworks.

我的问题是试图获得当前速度总是给我一个负值，我带着我的 iPhone 到了 3g 信号良好的地方，没关系，location.speed 值总是 -1.

My problem is trying to get the current speed always returns me a negative value, i have take my iPhone with me to places with a good 3g signal and it doesn't matter, location.speed value is always -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:

then 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;
    }



}

最后在我实现协议的视图控制器中:

and finally in the view controller in which I'm implementing the protocol:

- (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];
}

我快疯了，所以如果有人知道任何解决方案，那肯定会有所帮助.谢谢

Im getting crazy so if anyone knows any solution it will be helpful for sure. Thanks

推荐答案

通常，如果使用的位置检测机制不支持，您会得到负高度和速度.例如，当使用 Wi-Fi 或小区三角测量时.你确定，你正在获取 GPS 更新，所以你是在自由的天空下测试吗?即便如此，您仍会收到 WiFi 和手机信号塔位置更新，因此您必须将它们过滤掉.

Usually, you get negative altitude and speed if the used location detection mechanism doesn't support it. For instance, when Wi-Fi or cell triangulation is used. Are you sure, you're getting GPS updates, so are you testing under the free sky? Even then, you'll still receive WiFi and cell tower location updates so you've to filter them out.

Wi-Fi 位置更新的典型水平精度为 65 m.

65 m horizontal accuracy is typical for Wi-Fi location updates.

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