高德座標與谷歌座標互相轉換

一、常識：

目前常見的座標系有三種：地球座標（WGS84，國際公認座標，標準座標），火星座標（GCJ02，國家標準，適用於高德百度地圖大陸+港澳部分、Google地圖大陸部分），百度座標（BD09，適用於百度地圖大陸+港澳臺部分）。

二、代碼：

1、地球座標轉火星座標

+(CLLocationCoordinate2D)WGS84ToGCJ02transform:(double) wgLon lat:(double) wgLat
{
    const double a = 6378245.0;
    const double ee = 0.00669342162296594323;
    double mgLon;
    double mgLat;
    if ([self outOfChina:wgLat lon:wgLon])
    {
        mgLat = wgLat;
        mgLon = wgLon;
        return CLLocationCoordinate2DMake(mgLat, mgLon);
    }

    double dLat = [self transformLat:wgLon - 105.0 y:wgLat - 35.0];
    double dLon = [self transformLon:wgLon - 105.0 y:wgLat - 35.0];
    double radLat = wgLat / 180.0 * M_PI;
    double magic = sin(radLat);
    magic = 1 - ee * magic * magic;
    double sqrtMagic = sqrt(magic);
    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * M_PI);
    dLon = (dLon * 180.0) / (a / sqrtMagic * cos(radLat) * M_PI);
    mgLat = wgLat + dLat;
    mgLon = wgLon + dLon;
    return CLLocationCoordinate2DMake(mgLat, mgLon);
}

2、火星座標轉地球座標

//GCJ02->WGS84座標轉換
+ (CLLocationCoordinate2D)GCJ02TOWGS84WithSlat:(double)sLat SLng:(double)sLng {
    CLLocationCoordinate2D tCoord = [PublicOjbect transform:sLng lat:sLat];
    double lontitude = sLng * 2 - tCoord.longitude;
    double latitude = sLat * 2 - tCoord.latitude;
    return CLLocationCoordinate2DMake(latitude, lontitude);
}

3、公共代碼部分用於上述兩種算法：

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

+ (double)transformLon:(double) x y:(double) y
{
    double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(fabs(x));
    ret += (20.0 * sin(6.0 * x * M_PI) + 20.0 * sin(2.0 * x * M_PI)) * 2.0 / 3.0;
    ret += (20.0 * sin(x * M_PI) + 40.0 * sin(x / 3.0 * M_PI)) * 2.0 / 3.0;
    ret += (150.0 * sin(x / 12.0 * M_PI) + 300.0 * sin(x / 30.0 * M_PI)) * 2.0 / 3.0;
    return ret;
}

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