计算2坐标之间的距离iphone - 最佳实践

Question

我正在完成一个应用程序希望我需要向用户显示他和大约500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

谢谢大家,

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
}