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：
下面附上高德地图转换为自家经纬度坐标的链接：
下面提供一个无联网环境下的坐标转化算法， 参考
话不多说，直接上源代码：
YQLocationTransform.h文件
#import@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复制代码
YQLocationTransform.m文件
#import "YQLocationTransform.h"#importstatic 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复制代码
用法如下：
YQLocationTransform *beforeLocation = [[YQLocationTransform alloc] initWithLatitude:22.549522 andLongitude:113.947933];//百度转化为GPSYQLocationTransform *afterLocation = [beforeLocation transformFromBDToGPS];NSLog(@"转化后:%f, %f", afterLocation.latitude, afterLocation.longitude);复制代码