Question

我正在完成一个应用程序，希望我需要向用户显示他与大约500个坐标之间的距离。

使用CLLocation方法计算它，效果很好，但在iPhone 4中大约需要1分钟才能完成每个位置的计算。

最好的方法是什么？用span？还有其他更快的方法吗？

全心全意，

瑞

Answer 1

我认为Sahgal是对的，这里有一些代码，也许它会帮助你。

+(CGFloat)calculateDistanceBetweenSource:(CLLocationCoordinate2D)firstCoords andDestination:(CLLocationCoordinate2D)secondCoords 
{

    // this radius is in KM => if miles are needed it is calculated during setter of Place.distance

    double nRadius = 6371;

    // Get the difference between our two points

    // then convert the difference into radians

    double nDLat = (firstCoords.latitude - secondCoords.latitude)* (M_PI/180);
    double nDLon = (firstCoords.longitude - secondCoords.longitude)* (M_PI/180);

    double nLat1 =  secondCoords.latitude * (M_PI/180);
    double nLat2 =  secondCoords.latitude * (M_PI/180);

    double nA = pow ( sin(nDLat/2), 2 ) + cos(nLat1) * cos(nLat2) * pow ( sin(nDLon/2), 2 );

    double nC = 2 * atan2( sqrt(nA), sqrt( 1 - nA ));

    double nD = nRadius * nC;

    NSLog(@"Distance is %f",nD);

    return nD; // converts to miles or not (if en_) => implicit in method
}

Answer 2

我已经看到了其他答案，不知道它们是否正确，但我认为有更好的解决方案：

(from documentation):

- (CLLocationDistance)distanceFromLocation:(const CLLocation *)location

你可以像这样使用它：

- (CLLocationDistance) DistanceBetweenCoordinate:(CLLocationCoordinate2D)originCoordinate andCoordinate:(CLLocationCoordinate2D)destinationCoordinate {

        CLLocation *originLocation = [[CLLocation alloc] initWithLatitude:originCoordinate.latitude longitude:originCoordinate.longitude];
        CLLocation *destinationLocation = [[CLLocation alloc] initWithLatitude:destinationCoordinate.latitude longitude:destinationCoordinate.longitude];
        CLLocationDistance distance = [originLocation distanceFromLocation:destinationLocation];
        [originLocation release];
        [destinationLocation release];

        return distance;
    }

Answer 3

这是代码..

-(NSString *)findDistanceBetweenTwoLatLon
{
    int intEarthRadius = 3963;

    double dblLat1 = DegreesToRadians(firstLatitude);
    double dblLon1 = DegreesToRadians(firstLongitude);

    double dblLat2 = DegreesToRadians(secondLatitude);
    double dblLon2 = DegreesToRadians(secondLongitude);

    float fltLat = dblLat2 - dblLat1;
    float fltLon = dblLon2 - dblLon1;

    double a = sin(fltLat/2) * sin(fltLat/2) + cos(dblLat2) * cos(dblLat2) * sin(fltLon/2) * sin(fltLon/2) ;
    double c = 2 * atan2(sqrt(a), sqrt(1-a));
    double d = intEarthRadius * c;

    double dMeters = d * kOneMileMeters;

    NSString *strDistance = [NSString stringWithFormat:@"%1.2f meters",dMeters];

    return strDistance;
}

定义所有这个宏..

和度数到弧度

#define DegreesToRadians(degrees) (degrees * M_PI / 180)

其中M_PI

#define M_PI   3.14159265358979323846264338327950288 
#define kOneMileMeters 1609.344

Answer 4

你可以尝试另一种方法。你可以获取两个点的lat-long（假设lat-long发现不会花费那么多时间），并且有一些公式可以使用lat-long来计算距离。

计算2坐标之间的距离iphone - 最佳实践

4 个答案: