通过计算进行GPS坐标、火星坐标与百度坐标间的转换。不需数据库和联网。

通过计算进行GPS坐标、火星坐标与百度坐标间的转换。
不需数据库和联网。
注：转换算法会定期改变，但周期应该比较长。（目前的使用看来仍然可用）
在网上看到的一个方法，具体是修改自这份代码：
https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936

  
// 百度坐标转谷歌坐标

const CGFloat x_pi = 3.14159265358979324 * 3000.0 / 180.0;

+ (void)transformatBDLat:(CGFloat)fBDLat BDLng:(CGFloat)fBDLng toGoogleLat:(CGFloat *)pfGoogleLat googleLng:(CGFloat *)pfGoogleLng
{

    CGFloat x = fBDLng - 0.0065f, y = fBDLat - 0.006f;

    CGFloat z = sqrt(x * x + y * y) - 0.00002f * sin(y * x_pi);

    CGFloat theta = atan2(y, x) - 0.000003f * cos(x * x_pi);

    *pfGoogleLng = z * cos(theta);

    *pfGoogleLat = z * sin(theta);

}

+ (CLLocationCoordinate2D)getGoogleLocFromBaiduLocLat:(CGFloat)fBaiduLat lng:(CGFloat)fBaiduLng

{

    CGFloat fLat;

    CGFloat fLng;

    [[self class] transformatBDLat:fBaiduLat BDLng:fBaiduLng toGoogleLat:&fLat; googleLng:&fLng;];

    CLLocationCoordinate2D objLoc;

    objLoc.latitude = fLat;

    objLoc.longitude = fLng;

    return objLoc;

}

// 谷歌坐标转百度坐标

+ (CLLocationCoordinate2D)getBaiduLocFromGoogleLocLat:(CGFloat)fGoogleLat lng:(CGFloat)fGoogleLng

{

    CLLocationCoordinate2D objLoc;

    CGFloat x = fGoogleLng, y = fGoogleLat;

    CGFloat z = sqrt(x * x + y * y) + 0.00002f * sin(y * x_pi);

    CGFloat theta = atan2(y, x) + 0.000003f * cos(x * x_pi);

    objLoc.longitude = z * cos(theta) + 0.0065;

    objLoc.latitude = z * sin(theta) + 0.006;

    return objLoc;

}

/*******************       === GPS-Google  BEGIN  ===    *******************/

/*               在网上看到的根据这个 c# 代码改的 GPS坐标转火星坐标               */

/*  https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936  */

/***************************************************************************/

const double pi = 3.14159265358979324;

//

// Krasovsky 1940

//

// a = 6378245.0, 1/f = 298.3

// b = a * (1 - f)

// ee = (a^2 - b^2) / a^2;

const double a = 6378245.0;

const double ee = 0.00669342162296594323;

bool outOfChina(double lat, double lon);

static double transformLat(double x, double y);

static double transformLon(double x, double y);

// World Geodetic System ==> Mars Geodetic System

CLLocationCoordinate2D transformFromWGSCoord2MarsCoord(CLLocationCoordinate2D wgsCoordinate)

{

    double wgLat = wgsCoordinate.latitude;

    double wgLon = wgsCoordinate.longitude;

    if (outOfChina(wgLat, wgLon))

    {

        return wgsCoordinate;

    }

    double dLat = transformLat(wgLon - 105.0, wgLat - 35.0);

    double dLon = transformLon(wgLon - 105.0, wgLat - 35.0);

    double radLat = wgLat / 180.0 * pi;

    double magic = sin(radLat);

    magic = 1 - ee * magic * magic;

    double sqrtMagic = sqrt(magic);

    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);

    dLon = (dLon * 180.0) / (a / sqrtMagic * cos(radLat) * pi);

    CLLocationCoordinate2D marsCoordinate = {wgLat + dLat, wgLon + dLon};

    return marsCoordinate;

}

bool outOfChina(double lat, double lon)
{
    if (lon < 72.004 || lon > 137.8347)
        return true;
    if (lat < 0.8293 || lat > 55.8271)
        return true;
    return false;
}

double transformLat(double x, double y)
{
    double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * sqrt(abs(x));
    ret += (20.0 * sin(6.0 * x * pi) + 20.0 * sin(2.0 * x * pi)) * 2.0 / 3.0;
    ret += (20.0 * sin(y * pi) + 40.0 * sin(y / 3.0 * pi)) * 2.0 / 3.0;
    ret += (160.0 * sin(y / 12.0 * pi) + 320 * sin(y * pi / 30.0)) * 2.0 / 3.0;
    return ret;
}

double transformLon(double x, double y)
{
    double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(abs(x));
    ret += (20.0 * sin(6.0 * x * pi) + 20.0 * sin(2.0 * x * pi)) * 2.0 / 3.0;
    ret += (20.0 * sin(x * pi) + 40.0 * sin(x / 3.0 * pi)) * 2.0 / 3.0;
    ret += (150.0 * sin(x / 12.0 * pi) + 300.0 * sin(x / 30.0 * pi)) * 2.0 / 3.0;
    return ret;
}
/*******************       === GPS-Google  END  ===    *******************/
// GPS坐标转谷歌坐标
+ (CLLocationCoordinate2D)GPSLocToGoogleLoc:(CLLocationCoordinate2D)objGPSLoc
{
    return transformFromWGSCoord2MarsCoord(objGPSLoc);
}