『导言』
iOS 开发使用苹果原生地图时候，需要将地球坐标转化为火星坐标。为啥呢？如何转换？分析如下：
既然是在国内，存储⼀律⽤⽕星坐标，利用MapKit框架开发可以精确（苹果原生的用CLLocation定位的是真实经纬度坐标，即地球坐标；但在“国内苹果原生地图的数据是由高德地图提供”，所以需要将地球坐标转成火星坐标；可以用第三方库CLLocation+Sino来实现转换；否则使用会有偏差。CLLocation+Sino的Demo下载
温馨提示：
- 如果用
高德、百度等第三方SDK进行开发，他们内部做了转换，所以不需要转换。
- 如果使用
苹果原生地图需要地球坐标转火星坐标。
重点代码：
地球地址转化为火星地址
location = [location locationMarsFromEarth];
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
NSLog(@"定位成功");
//获取当前位置----是地球地址(国际地址)
//manager.location
CLLocation *location = manager.location;
//地球地址转化为火星地址
location = [location locationMarsFromEarth];
//地图的中心点设置为当前位置
// 苹果地图使用的是火星地址
_mapView.centerCoordinate = location.coordinate;
[_locationManager stopUpdatingLocation];
}
CLLocation+Sino.h
//
// CLLocation+Sino.h
//
// Created by [email protected] on 13-4-26.
// 火星坐标系转换扩展
//
// earth（国外 WGS84）, mars（国内 GCJ-02）, bearPaw（百度 BD-09） 坐标系间相互转换
// 未包含 mars2earth. 需要这个可参考 http://xcodev.com/131.html
#import
@interface CLLocation (Sino)
- (CLLocation*)locationMarsFromEarth;
//- (CLLocation*)locationEarthFromMars; // 未实现
- (CLLocation*)locationBearPawFromMars;
- (CLLocation*)locationMarsFromBearPaw;
@end
CLLocation+Sino.m
//
// CLLocation+Sino.h
//
// Created by [email protected] on 13-4-26.
// 火星坐标系转换扩展
#import "CLLocation+Sino.h"
void transform_earth_2_mars(double lat, double lng, double* tarLat, double* tarLng);
void transform_mars_2_bear_paw(double lat, double lng, double* tarLat, double* tarLng);
void transform_bear_paw_2_mars(double lat, double lng, double* tarLat, double* tarLng);
@implementation CLLocation (Sino)
- (CLLocation*)locationMarsFromEarth;
{
double lat = 0.0;
double lng = 0.0;
transform_earth_2_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*)locationEarthFromMars;
{
// 二分法查纠偏文件
// http://xcodev.com/131.html
return nil;
}
- (CLLocation*)locationBearPawFromMars;
{
double lat = 0.0;
double lng = 0.0;
transform_mars_2_bear_paw(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*)locationMarsFromBearPaw;
{
double lat = 0.0;
double lng = 0.0;
transform_bear_paw_2_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];
}
@end
// --- transform_earth_2_mars ---
// 参考来源：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_2_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_2_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_2_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_2_mars_lat(lng - 105.0, lat - 35.0);
double dLon = transform_earth_2_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 = lat + dLat;
*tarLng = lng + dLon;
}
// --- transform_earth_2_mars end ---
// --- transform_mars_vs_bear_paw ---
// 参考来源：http://blog.woodbunny.com/post-68.html
const double x_pi = M_PI * 3000.0 / 180.0;
void transform_mars_2_bear_paw(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_bear_paw_2_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);
}
// --- transform_mars_vs_bear_paw end ---
温馨提示：如下'链接'为我写的升级版地图相关。
iOS 火星坐标/地球坐标/百度坐标整理及解决方案汇总？如何转火星坐标？
参考链接：
[1].ios 百度地图，火星坐标，地球坐标互转