ios 座標系的轉換

#import <CoreLocation/CoreLocation.h>

@interface CLLocation (YCLocation)
//從地圖座標轉化到火星座標
- (CLLocation*)locationMarsFromEarth;

//從火星座標轉化到百度座標
- (CLLocation*)locationBaiduFromMars;

//從百度座標到火星座標
- (CLLocation*)locationMarsFromBaidu;

//從火星座標到地圖座標
- (CLLocation*)locationEarthFromMars;

//從百度座標到地圖座標
- (CLLocation*)locationEarthFromBaidu;
@end

//
//  CLLocation+YCLocation.m
//  37duc
//
//  Created by Tony on 16/4/5.
//  Copyright © 2016年 37service. All rights reserved.
//

#import "CLLocation+YCLocation.h"

void transform_earth_from_mars(double lat, double lng, double* tarLat, double* tarLng);
void transform_mars_from_baidu(double lat, double lng, double* tarLat, double* tarLng);
void transform_baidu_from_mars(double lat, double lng, double* tarLat, double* tarLng);

@implementation CLLocation (YCLocation)

- (CLLocation*)locationMarsFromEarth
{
    double lat = 0.0;
    double lng = 0.0;
    transform_earth_from_mars(self.coordinate.latitude, self.coordinate.longitude, &lat, &lng);
    return [[CLLocation alloc] initWithCoordinate:CLLocationCoordinate2DMake(lat+self.coordinate.latitude, lng+self.coordinate.longitude)
                                         altitude:self.altitude
                               horizontalAccuracy:self.horizontalAccuracy
                                 verticalAccuracy:self.verticalAccuracy
                                           course:self.course
                                            speed:self.speed
                                        timestamp:self.timestamp];
}

- (CLLocation*)locationEarthFromMars
{
    double lat = 0.0;
    double lng = 0.0;
    transform_earth_from_mars(self.coordinate.latitude, self.coordinate.longitude, &lat, &lng);
    return [[CLLocation alloc] initWithCoordinate:CLLocationCoordinate2DMake(self.coordinate.latitude-lat, self.coordinate.longitude-lng)
                                         altitude:self.altitude
                               horizontalAccuracy:self.horizontalAccuracy
                                 verticalAccuracy:self.verticalAccuracy
                                           course:self.course
                                            speed:self.speed
                                        timestamp:self.timestamp];
    return nil;
}

- (CLLocation*)locationBaiduFromMars
{
    double lat = 0.0;
    double lng = 0.0;
    transform_mars_from_baidu(self.coordinate.latitude, self.coordinate.longitude, &lat, &lng);
    return [[CLLocation alloc] initWithCoordinate:CLLocationCoordinate2DMake(lat, lng)
                                         altitude:self.altitude
                               horizontalAccuracy:self.horizontalAccuracy
                                 verticalAccuracy:self.verticalAccuracy
                                           course:self.course
                                            speed:self.speed
                                        timestamp:self.timestamp];
}

- (CLLocation*)locationMarsFromBaidu
{
    double lat = 0.0;
    double lng = 0.0;
    transform_baidu_from_mars(self.coordinate.latitude, self.coordinate.longitude, &lat, &lng);
    return [[CLLocation alloc] initWithCoordinate:CLLocationCoordinate2DMake(lat, lng)
                                         altitude:self.altitude
                               horizontalAccuracy:self.horizontalAccuracy
                                 verticalAccuracy:self.verticalAccuracy
                                           course:self.course
                                            speed:self.speed
                                        timestamp:self.timestamp];
}

-(CLLocation*)locationEarthFromBaidu
{
    double lat = 0.0;
    double lng = 0.0;
    CLLocation *Mars = [self locationMarsFromBaidu];
    
    transform_earth_from_mars(Mars.coordinate.latitude, Mars.coordinate.longitude, &lat, &lng);
    return [[CLLocation alloc] initWithCoordinate:CLLocationCoordinate2DMake(Mars.coordinate.latitude-lat, Mars.coordinate.longitude-lng)
                                         altitude:self.altitude
                               horizontalAccuracy:self.horizontalAccuracy
                                 verticalAccuracy:self.verticalAccuracy
                                           course:self.course
                                            speed:self.speed
                                        timestamp:self.timestamp];
    return nil;
}

@end



// --- transform_earth_from_mars ---
// 參考來源：https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936
// 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 transform_sino_out_china(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 transform_earth_from_mars_lat(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 * 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 transform_earth_from_mars_lng(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 * 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;
}

void transform_earth_from_mars(double lat, double lng, double* tarLat, double* tarLng)
{
    if (transform_sino_out_china(lat, lng))
    {
        *tarLat = lat;
        *tarLng = lng;
        return;
    }
    double dLat = transform_earth_from_mars_lat(lng - 105.0, lat - 35.0);
    double dLon = transform_earth_from_mars_lng(lng - 105.0, lat - 35.0);
    double radLat = lat / 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);
    *tarLat = dLat;
    *tarLng = dLon;
}

// --- transform_earth_from_mars end ---
// --- transform_mars_vs_bear_paw ---
// 參考來源：http://blog.woodbunny.com/post-68.html
const double x_pi = M_PI * 3000.0 / 180.0;

void transform_mars_from_baidu(double gg_lat, double gg_lon, double *bd_lat, double *bd_lon)
{
    double x = gg_lon, y = gg_lat;
    double z = sqrt(x * x + y * y) + 0.00002 * sin(y * x_pi);
    double theta = atan2(y, x) + 0.000003 * cos(x * x_pi);
    *bd_lon = z * cos(theta) + 0.0065;
    *bd_lat = z * sin(theta) + 0.006;
}

void transform_baidu_from_mars(double bd_lat, double bd_lon, double *gg_lat, double *gg_lon)
{
    double x = bd_lon - 0.0065, y = bd_lat - 0.006;
    double z = sqrt(x * x + y * y) - 0.00002 * sin(y * x_pi);
    double theta = atan2(y, x) - 0.000003 * cos(x * x_pi);
    *gg_lon = z * cos(theta);
    *gg_lat = z * sin(theta);
}