GPS以及iOS系统定位获得的坐标是地理坐标系WGS1984，Web地图一般用的坐标细是投影坐标系WGS 1984 Web Mercator，国内出于相关法律法规要求，对国内所有GPS设备及地图数据都进行了加密偏移处理，代号GCJ-02，这样GPS定位获得的坐标与地图上的位置刚好对应上，特殊的是百度地图在这基础上又进行一次偏移，所以在处理系统定位坐标及相关地图SDK坐标时需要转换处理下，根据网络资源，目前有一些公开的转换算法。
系统定位坐标显示在原生地图、谷歌地图或高德地图–WGS1984转GCJ-02
苹果地图及谷歌地图用的都是高德地图的数据，所以这三种情况坐标处理方法一样，即将WGS1984坐标转换成偏移后的GCJ-02才可以在地图上正确显示位置。
通过这个工具类可将iOS原生地图获取的坐标点转换为地图上正确表示的真实坐标点:
.h
//// GPSLocationTool.h// Zar//// Created by carayfire－Develop on 16/6/8.// Copyright © Crazyfire technology development Co. Ltd. All rights reserved.//#import <Foundation/Foundation.h>#import <CoreLocation/CoreLocation.h>@interface GPSLocationTool : NSObject/*** public:原生地图获取坐标转化为真实坐标** @param latLng 原生坐标点** @return 真实坐标点*/+ (CLLocationCoordinate2D)transform:(CLLocationCoordinate2D)latLng;@end
.m
//// GPSLocationTool.m// Zar//// Created by carayfire－Develop on 16/6/8.// Copyright © Crazyfire technology development Co. Ltd. All rights reserved.//#import "GPSLocationTool.h"#import <CoreLocation/CoreLocation.h>@implementation GPSLocationToolconst double a = 6378245.0;const double ee = 0.00669342162296594323;/*** public:原生地图获取坐标转化为真实坐标** @param latLng 原生坐标点** @return 真实坐标点*/+ (CLLocationCoordinate2D)transform:(CLLocationCoordinate2D) latLng{double wgLat = latLng.latitude;double wgLon = latLng.longitude;double mgLat;double mgLon;if ([self outOfChina:wgLat :wgLon ]){return latLng;}double dLat = [self transformLat:wgLon-105.0 :wgLat - 35 ];double dLon = [self transformLon:wgLon-105.0 :wgLat - 35 ];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;CLLocationCoordinate2D loc2D ;loc2D.latitude = mgLat;loc2D.longitude = mgLon;return loc2D;}#pragma mark private+ (BOOL) outOfChina:(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) transformLat:(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(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 :(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;}@end
