地图定位不准问题

同一个经纬度坐标在iOS端和Android端出现了比较大偏差。查了下资料苹果地图在大陆的数据源是高德的，查了下高德采用GCJ-02, 百度map sdk 采用的是BD-09，只好写了个类在发送和接收时做好转换，略微蛋疼。Github上有人写了一个现成的转换类，可以参考参考 传送门 ，其主要代码见下：

头文件：

#import <Foundation/Foundation.h>
#import <CoreLocation/CoreLocation.h>
@interface JZLocationConverter : NSObject

/**
*	@brief	世界标准地理坐标(WGS-84) 转换成 中国国测局地理坐标（GCJ-02）<火星坐标>
*
*  ####只在中国大陆的范围的坐标有效，以外直接返回世界标准坐标
*
*	@param 	location 	世界标准地理坐标(WGS-84)
*
*	@return	中国国测局地理坐标（GCJ-02）<火星坐标>
*/
+ (CLLocationCoordinate2D)wgs84ToGcj02:(CLLocationCoordinate2D)location;

/**
*	@brief	中国国测局地理坐标（GCJ-02） 转换成 世界标准地理坐标（WGS-84）
*
*  ####此接口有1－2米左右的误差，需要精确定位情景慎用
*
*	@param 	location 	中国国测局地理坐标（GCJ-02）
*
*	@return	世界标准地理坐标（WGS-84）
*/
+ (CLLocationCoordinate2D)gcj02ToWgs84:(CLLocationCoordinate2D)location;

/**
*	@brief	世界标准地理坐标(WGS-84) 转换成 百度地理坐标（BD-09)
*
*	@param 	location 	世界标准地理坐标(WGS-84)
*
*	@return	百度地理坐标（BD-09)
*/
+ (CLLocationCoordinate2D)wgs84ToBd09:(CLLocationCoordinate2D)location;

/**
*	@brief	中国国测局地理坐标（GCJ-02）<火星坐标> 转换成 百度地理坐标（BD-09)
*
*	@param 	location 	中国国测局地理坐标（GCJ-02）<火星坐标>
*
*	@return	百度地理坐标（BD-09)
*/
+ (CLLocationCoordinate2D)gcj02ToBd09:(CLLocationCoordinate2D)location;

/**
*	@brief	百度地理坐标（BD-09) 转换成 中国国测局地理坐标（GCJ-02）<火星坐标>
*
*	@param 	location 	百度地理坐标（BD-09)
*
*	@return	中国国测局地理坐标（GCJ-02）<火星坐标>
*/
+ (CLLocationCoordinate2D)bd09ToGcj02:(CLLocationCoordinate2D)location;

/**
*	@brief	百度地理坐标（BD-09) 转换成 世界标准地理坐标（WGS-84）
*
*  ####此接口有1－2米左右的误差，需要精确定位情景慎用
*
*	@param 	location 	百度地理坐标（BD-09)
*
*	@return	世界标准地理坐标（WGS-84）
*/
+ (CLLocationCoordinate2D)bd09ToWgs84:(CLLocationCoordinate2D)location;

@end

实现文件

#import "JZLocationConverter.h"
#import <CoreLocation/CoreLocation.h>
#define LAT_OFFSET_0(x,y) -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * sqrt(fabs(x))
#define LAT_OFFSET_1 (20.0 * sin(6.0 * x * M_PI) + 20.0 * sin(2.0 * x * M_PI)) * 2.0 / 3.0
#define LAT_OFFSET_2 (20.0 * sin(y * M_PI) + 40.0 * sin(y / 3.0 * M_PI)) * 2.0 / 3.0
#define LAT_OFFSET_3 (160.0 * sin(y / 12.0 * M_PI) + 320 * sin(y * M_PI / 30.0)) * 2.0 / 3.0

#define LON_OFFSET_0(x,y) 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(fabs(x))
#define LON_OFFSET_1 (20.0 * sin(6.0 * x * M_PI) + 20.0 * sin(2.0 * x * M_PI)) * 2.0 / 3.0
#define LON_OFFSET_2 (20.0 * sin(x * M_PI) + 40.0 * sin(x / 3.0 * M_PI)) * 2.0 / 3.0
#define LON_OFFSET_3 (150.0 * sin(x / 12.0 * M_PI) + 300.0 * sin(x / 30.0 * M_PI)) * 2.0 / 3.0

#define RANGE_LON_MAX 137.8347
#define RANGE_LON_MIN 72.004
#define RANGE_LAT_MAX 55.8271
#define RANGE_LAT_MIN 0.8293
// jzA = 6378245.0, 1/f = 298.3
// b = a * (1 - f)
// ee = (a^2 - b^2) / a^2;
#define jzA 6378245.0
#define jzEE 0.00669342162296594323

@implementation JZLocationConverter

+ (double)transformLat:(double)x bdLon:(double)y
{
double ret = LAT_OFFSET_0(x, y);
ret += LAT_OFFSET_1;
ret += LAT_OFFSET_2;
ret += LAT_OFFSET_3;
return ret;
}

+ (double)transformLon:(double)x bdLon:(double)y
{
double ret = LON_OFFSET_0(x, y);
ret += LON_OFFSET_1;
ret += LON_OFFSET_2;
ret += LON_OFFSET_3;
return ret;
}

+ (BOOL)outOfChina:(double)lat bdLon:(double)lon
{
if (lon < RANGE_LON_MIN || lon > RANGE_LON_MAX)
return true;
if (lat < RANGE_LAT_MIN || lat > RANGE_LAT_MAX)
return true;
return false;
}

+ (CLLocationCoordinate2D)gcj02Encrypt:(double)ggLat bdLon:(double)ggLon
{
CLLocationCoordinate2D resPoint;
double mgLat;
double mgLon;
if ([self outOfChina:ggLat bdLon:ggLon]) {
resPoint.latitude = ggLat;
resPoint.longitude = ggLon;
return resPoint;
}
double dLat = [self transformLat:(ggLon - 105.0)bdLon:(ggLat - 35.0)];
double dLon = [self transformLon:(ggLon - 105.0) bdLon:(ggLat - 35.0)];
double radLat = ggLat / 180.0 * M_PI;
double magic = sin(radLat);
magic = 1 - jzEE * magic * magic;
double sqrtMagic = sqrt(magic);
dLat = (dLat * 180.0) / ((jzA * (1 - jzEE)) / (magic * sqrtMagic) * M_PI);
dLon = (dLon * 180.0) / (jzA / sqrtMagic * cos(radLat) * M_PI);
mgLat = ggLat + dLat;
mgLon = ggLon + dLon;

resPoint.latitude = mgLat;
resPoint.longitude = mgLon;
return resPoint;
}

+ (CLLocationCoordinate2D)gcj02Decrypt:(double)gjLat gjLon:(double)gjLon {
CLLocationCoordinate2D  gPt = [self gcj02Encrypt:gjLat bdLon:gjLon];
double dLon = gPt.longitude - gjLon;
double dLat = gPt.latitude - gjLat;
CLLocationCoordinate2D pt;
pt.latitude = gjLat - dLat;
pt.longitude = gjLon - dLon;
return pt;
}

+ (CLLocationCoordinate2D)bd09Decrypt:(double)bdLat bdLon:(double)bdLon
{
CLLocationCoordinate2D gcjPt;
double x = bdLon - 0.0065, y = bdLat - 0.006;
double z = sqrt(x * x + y * y) - 0.00002 * sin(y * M_PI);
double theta = atan2(y, x) - 0.000003 * cos(x * M_PI);
gcjPt.longitude = z * cos(theta);
gcjPt.latitude = z * sin(theta);
return gcjPt;
}

+(CLLocationCoordinate2D)bd09Encrypt:(double)ggLat bdLon:(double)ggLon
{
CLLocationCoordinate2D bdPt;
double x = ggLon, y = ggLat;
double z = sqrt(x * x + y * y) + 0.00002 * sin(y * M_PI);
double theta = atan2(y, x) + 0.000003 * cos(x * M_PI);
bdPt.longitude = z * cos(theta) + 0.0065;
bdPt.latitude = z * sin(theta) + 0.006;
return bdPt;
}

+ (CLLocationCoordinate2D)wgs84ToGcj02:(CLLocationCoordinate2D)location
{
return [self gcj02Encrypt:location.latitude bdLon:location.longitude];
}

+ (CLLocationCoordinate2D)gcj02ToWgs84:(CLLocationCoordinate2D)location
{
return [self gcj02Decrypt:location.latitude gjLon:location.longitude];
}

+ (CLLocationCoordinate2D)wgs84ToBd09:(CLLocationCoordinate2D)location
{
CLLocationCoordinate2D gcj02Pt = [self gcj02Encrypt:location.latitude
bdLon:location.longitude];
return [self bd09Encrypt:gcj02Pt.latitude bdLon:gcj02Pt.longitude] ;
}

+ (CLLocationCoordinate2D)gcj02ToBd09:(CLLocationCoordinate2D)location
{
return  [self bd09Encrypt:location.latitude bdLon:location.longitude];
}

+ (CLLocationCoordinate2D)bd09ToGcj02:(CLLocationCoordinate2D)location
{
return [self bd09Decrypt:location.latitude bdLon:location.longitude];
}

+ (CLLocationCoordinate2D)bd09ToWgs84:(CLLocationCoordinate2D)location
{
CLLocationCoordinate2D gcj02 = [self bd09ToGcj02:location];
return [self gcj02Decrypt:gcj02.latitude gjLon:gcj02.longitude];
}

@end

测试用例：

CLLocationCoordinate2D gcj02 = CLLocationCoordinate2DMake(114.21892734521,29.575429778924);
CLLocationCoordinate2D bd09 = [JZLocationConverter gcj02ToBd09:gcj02];
NSLog(@"%f,%f", bd09.latitude, bd09.longitude);

// http://developer.baidu.com/map/index.php?title=webapi/guide/changeposition // JZLocationConverter 测试数据: 114.21892734521,29.575429778924  ; 转化结果: 114.224960,29.581853
// 百度api  测试数据: 114.21892734521,29.575429778924  ; 百度api转换结果: 114.22539195429,29.581585367458

总体来说，存在一点偏差，但跟处理前的效果比一下，相对可以接受了些。

参考：
http://blog.csdn.net/jiajiayouba/article/details/25140967 http://developer.baidu.com/map/index.php?title=webapi/guide/changeposition http://blog.csdn.net/winnyrain/article/details/22233559 http://www.kuaifenxiang.net/article/17 http://blog.csdn.net/coolypf/article/details/8569813 http://www.cppblog.com/socketref/archive/2011/06/29/149713.html
原文：http://www.tuicool.com/articles/fMzYNrz