常用地图坐标系介绍：
- WGS-84：是国际标准，GPS坐标（Google Earth使用、或者GPS模块）
- GCJ-02：中国坐标偏移标准，Google地图、高德、腾讯使用
- BD-09 ：百度坐标偏移标准，Baidu地图使用
我们经常在常用的这几种地图中进行坐标转换，或用于第三方地图的导航，或用于后台下发地址的打点等等场景。虽然百度和高德都提供相应的api，但是他们都只提供向自家坐标系转化的api，需要连网请求才能得到转化后的结果。（前提还得申请他们开放平台的appKey）
下面附上百度地图转换为自家经纬度坐标的链接：
http://lbsyun.baidu.com/index.php?title=webapi/guide/changeposition
下面附上高德地图转换为自家经纬度坐标的链接：
http://lbsbbs.amap.com/forum.php?mod=viewthread&tid=724&extra=page%3D1
下面提供一个无联网环境下的坐标转化算法，
参考http://www.oschina.net/code/snippet_2296716_48678
话不多说，直接上源代码：
YQLocationTransform.h文件
#import <Foundation/Foundation.h>
@interface YQLocationTransform : NSObject
@property (nonatomic, assign) double latitude;
@property (nonatomic, assign) double longitude;
- (id)initWithLatitude:(double)latitude andLongitude:(double)longitude;
/*
坐标系：
WGS-84：是国际标准，GPS坐标（Google Earth使用、或者GPS模块）
GCJ-02：中国坐标偏移标准，Google Map、高德、腾讯使用
BD-09 ：百度坐标偏移标准，Baidu Map使用
*/
#pragma mark - 从GPS坐标转化到高德坐标
- (id)transformFromGPSToGD;
#pragma mark - 从高德坐标转化到百度坐标
- (id)transformFromGDToBD;
#pragma mark - 从百度坐标到高德坐标
- (id)transformFromBDToGD;
#pragma mark - 从高德坐标到GPS坐标
- (id)transformFromGDToGPS;
#pragma mark - 从百度坐标到GPS坐标
- (id)transformFromBDToGPS;
@end
YQLocationTransform.m文件
#import "YQLocationTransform.h"
#import <CoreLocation/CoreLocation.h>
static const double a = 6378245.0;
static const double ee = 0.00669342162296594323;
static const double pi = M_PI;
static const double xPi = M_PI * 3000.0 / 180.0;
@implementation YQLocationTransform
- (id)initWithLatitude:(double)latitude andLongitude:(double)longitude {
if (self = [super init]) {
self.latitude = latitude;
self.longitude = longitude;
}
return self;
}
- (id)transformFromGPSToGD {
CLLocationCoordinate2D coor = [ECLocationTransform transformFromWGSToGCJ:CLLocationCoordinate2DMake(self.latitude, self.longitude)];
return [[ECLocationTransform alloc] initWithLatitude:coor.latitude andLongitude:coor.longitude];
}
- (id)transformFromGDToBD {
CLLocationCoordinate2D coor = [ECLocationTransform transformFromGCJToBaidu:CLLocationCoordinate2DMake(self.latitude, self.longitude)];
return [[ECLocationTransform alloc] initWithLatitude:coor.latitude andLongitude:coor.longitude];
}
- (id)transformFromBDToGD {
CLLocationCoordinate2D coor = [ECLocationTransform transformFromBaiduToGCJ:CLLocationCoordinate2DMake(self.latitude, self.longitude)];
return [[ECLocationTransform alloc] initWithLatitude:coor.latitude andLongitude:coor.longitude];
}
- (id)transformFromGDToGPS {
CLLocationCoordinate2D coor = [ECLocationTransform transformFromGCJToWGS:CLLocationCoordinate2DMake(self.latitude, self.longitude)];
return [[ECLocationTransform alloc] initWithLatitude:coor.latitude andLongitude:coor.longitude];
}
- (id)transformFromBDToGPS {
//先把百度转化为高德
CLLocationCoordinate2D start_coor = [ECLocationTransform transformFromBaiduToGCJ:CLLocationCoordinate2DMake(self.latitude, self.longitude)];
CLLocationCoordinate2D end_coor = [ECLocationTransform transformFromGCJToWGS:CLLocationCoordinate2DMake(start_coor.latitude, start_coor.longitude)];
return [[ECLocationTransform alloc] initWithLatitude:end_coor.latitude andLongitude:end_coor.longitude];
}
+ (CLLocationCoordinate2D)transformFromWGSToGCJ:(CLLocationCoordinate2D)wgsLoc {
CLLocationCoordinate2D adjustLoc;
if([self isLocationOutOfChina:wgsLoc]) {
adjustLoc = wgsLoc;
}
else {
double adjustLat = [self transformLatWithX:wgsLoc.longitude - 105.0 withY:wgsLoc.latitude - 35.0];
double adjustLon = [self transformLonWithX:wgsLoc.longitude - 105.0 withY:wgsLoc.latitude - 35.0];
long double radLat = wgsLoc.latitude / 180.0 * pi;
long double magic = sin(radLat);
magic = 1 - ee * magic * magic;
long double sqrtMagic = sqrt(magic);
adjustLat = (adjustLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
adjustLon = (adjustLon * 180.0) / (a / sqrtMagic * cos(radLat) * pi);
adjustLoc.latitude = wgsLoc.latitude + adjustLat;
adjustLoc.longitude = wgsLoc.longitude + adjustLon;
}
return adjustLoc;
}
+ (double)transformLatWithX:(double)x withY:(double)y {
double lat = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * sqrt(fabs(x));
lat += (20.0 * sin(6.0 * x * pi) + 20.0 *sin(2.0 * x * pi)) * 2.0 / 3.0;
lat += (20.0 * sin(y * pi) + 40.0 * sin(y / 3.0 * pi)) * 2.0 / 3.0;
lat += (160.0 * sin(y / 12.0 * pi) + 320 * sin(y * pi / 30.0)) * 2.0 / 3.0;
return lat;
}
+ (double)transformLonWithX:(double)x withY:(double)y {
double lon = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(fabs(x));
lon += (20.0 * sin(6.0 * x * pi) + 20.0 * sin(2.0 * x * pi)) * 2.0 / 3.0;
lon += (20.0 * sin(x * pi) + 40.0 * sin(x / 3.0 * pi)) * 2.0 / 3.0;
lon += (150.0 * sin(x / 12.0 * pi) + 300.0 * sin(x / 30.0 * pi)) * 2.0 / 3.0;
return lon;
}
+ (CLLocationCoordinate2D)transformFromGCJToBaidu:(CLLocationCoordinate2D)p {
long double z = sqrt(p.longitude * p.longitude + p.latitude * p.latitude) + 0.00002 * sqrt(p.latitude * pi);
long double theta = atan2(p.latitude, p.longitude) + 0.000003 * cos(p.longitude * pi);
CLLocationCoordinate2D geoPoint;
geoPoint.latitude = (z * sin(theta) + 0.006);
geoPoint.longitude = (z * cos(theta) + 0.0065);
return geoPoint;
}
+ (CLLocationCoordinate2D)transformFromBaiduToGCJ:(CLLocationCoordinate2D)p {
double x = p.longitude - 0.0065, y = p.latitude - 0.006;
double z = sqrt(x * x + y * y) - 0.00002 * sin(y * xPi);
double theta = atan2(y, x) - 0.000003 * cos(x * xPi);
CLLocationCoordinate2D geoPoint;
geoPoint.latitude = z * sin(theta);
geoPoint.longitude = z * cos(theta);
return geoPoint;
}
+ (CLLocationCoordinate2D)transformFromGCJToWGS:(CLLocationCoordinate2D)p {
double threshold = 0.00001;
// The boundary
double minLat = p.latitude - 0.5;
double maxLat = p.latitude + 0.5;
double minLng = p.longitude - 0.5;
double maxLng = p.longitude + 0.5;
double delta = 1;
int maxIteration = 30;
// Binary search
while(true) {
CLLocationCoordinate2D leftBottom = [[self class] transformFromWGSToGCJ:(CLLocationCoordinate2D){.latitude = minLat,.longitude = minLng}];
CLLocationCoordinate2D rightBottom = [[self class] transformFromWGSToGCJ:(CLLocationCoordinate2D){.latitude = minLat,.longitude = maxLng}];
CLLocationCoordinate2D leftUp = [[self class] transformFromWGSToGCJ:(CLLocationCoordinate2D){.latitude = maxLat,.longitude = minLng}];
CLLocationCoordinate2D midPoint = [[self class] transformFromWGSToGCJ:(CLLocationCoordinate2D){.latitude = ((minLat + maxLat) / 2),.longitude = ((minLng + maxLng) / 2)}];
delta = fabs(midPoint.latitude - p.latitude) + fabs(midPoint.longitude - p.longitude);
if(maxIteration-- <= 0 || delta <= threshold) {
return (CLLocationCoordinate2D){.latitude = ((minLat + maxLat) / 2),.longitude = ((minLng + maxLng) / 2)};
}
if(isContains(p, leftBottom, midPoint)) {
maxLat = (minLat + maxLat) / 2;
maxLng = (minLng + maxLng) / 2;
} else if(isContains(p, rightBottom, midPoint)) {
maxLat = (minLat + maxLat) / 2;
minLng = (minLng + maxLng) / 2;
} else if(isContains(p, leftUp, midPoint)) {
minLat = (minLat + maxLat) / 2;
maxLng = (minLng + maxLng) / 2;
} else {
minLat = (minLat + maxLat) / 2;
minLng = (minLng + maxLng) / 2;
}
}
}
#pragma mark - 判断某个点point是否在p1和p2之间
static bool isContains(CLLocationCoordinate2D point, CLLocationCoordinate2D p1, CLLocationCoordinate2D p2) {
return (point.latitude >= MIN(p1.latitude, p2.latitude) && point.latitude <= MAX(p1.latitude, p2.latitude)) && (point.longitude >= MIN(p1.longitude,p2.longitude) && point.longitude <= MAX(p1.longitude, p2.longitude));
}
#pragma mark - 判断是不是在中国
+ (BOOL)isLocationOutOfChina:(CLLocationCoordinate2D)location {
if (location.longitude < 72.004 || location.longitude > 137.8347 || location.latitude < 0.8293 || location.latitude > 55.8271)
return YES;
return NO;
}
@end
用法如下：
YQLocationTransform *beforeLocation = [[YQLocationTransform alloc] initWithLatitude:22.549522 andLongitude:113.947933];
//百度转化为GPS
YQLocationTransform *afterLocation = [beforeLocation transformFromBDToGPS];
NSLog(@"转化后:%f, %f", afterLocation.latitude, afterLocation.longitude);
