(iPhone/iPad开发)由经纬度计算距离

有2种计算方法

一种是写一个算法自己手动计算

#pragma mark - calculate distance+(double) LantitudeLongitudeDist:(double)lon1 other_Lat:(double)lat1 self_Lon:(double)lon2 self_Lat:(double)lat2{    double er = 6378137; // 6378700.0f;//ave. radius = 6371.315 (someone said more accurate is 6366.707)//equatorial radius = 6378.388//nautical mile = 1.15078double radlat1 = PI*lat1/180.0f;double radlat2 = PI*lat2/180.0f;//now long.double radlong1 = PI*lon1/180.0f;double radlong2 = PI*lon2/180.0f;if( radlat1 < 0 ) radlat1 = PI/2 + fabs(radlat1);// southif( radlat1 > 0 ) radlat1 = PI/2 - fabs(radlat1);// northif( radlong1 < 0 ) radlong1 = PI*2 - fabs(radlong1);//westif( radlat2 < 0 ) radlat2 = PI/2 + fabs(radlat2);// southif( radlat2 > 0 ) radlat2 = PI/2 - fabs(radlat2);// northif( radlong2 < 0 ) radlong2 = PI*2 - fabs(radlong2);// west//spherical coordinates x=r*cos(ag)sin(at), y=r*sin(ag)*sin(at), z=r*cos(at)//zero ag is up so reverse latdouble x1 = er * cos(radlong1) * sin(radlat1);double y1 = er * sin(radlong1) * sin(radlat1);double z1 = er * cos(radlat1);double x2 = er * cos(radlong2) * sin(radlat2);double y2 = er * sin(radlong2) * sin(radlat2);double z2 = er * cos(radlat2);double d = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)+(z1-z2)*(z1-z2));//side, side, side, law of cosines and arccosdouble theta = acos((er*er+er*er-d*d)/(2*er*er));double dist  = theta*er;return dist;}

另一种，苹果公司sdk中已经封装好了

distanceFromLocation方法

CLLocation* orig=[[[CLLocation alloc] initWithLatitude:[mainDelegate.latitude_self doubleValue]  longitude:[mainDelegate.longitude_self doubleValue]] autorelease];            CLLocation* dist=[[[CLLocation alloc] initWithLatitude:[tmpNewsModel.latitude doubleValue] longitude:[tmpNewsModel.longitude doubleValue] ] autorelease];                        CLLocationDistance kilometers=[orig distanceFromLocation:dist]/1000;            NSLog(@"____^^^^^^_____kilometers:%0.2f 公里____________________",kilometers);