ios - how to draw an arrow between two points on the map? MapKit -

how draw arrow between 2 points on map?
try calc latitude , longitude, goes wrong.

best regards, max

this code , result picture

        int currpoints1 = 2;     nslog(@"!!!!!!!!%d ",numpoints);     while(currpoints1 < numpoints)     {          trackpoint* current = nil;         cllocationcoordinate2d* coordsarrrow = malloc((3) * sizeof(cllocationcoordinate2d));         (int =currpoints1, j=0; < numpoints; i=i+1, j++)         {             current = [cashpoints objectatindex:i];             coordsarrrow[j] = current.coordinate;             if (i % 2 !=0) {                 int gug = 30;                  int ug;                 float bx, by, ex, ey;                 bx = coordsarrrow[0].latitude;by = coordsarrrow[0].longitude;                 ex = coordsarrrow[1].latitude;ey = coordsarrrow[1].longitude;                 float lstr = sqrt((ex-ey)*(ex-ey)+(bx-by)*(bx-by));                 ug = [self retgradw:(abs(coordsarrrow[1].latitude-coordsarrrow[0].latitude)) height:abs(coordsarrrow[1].longitude-coordsarrrow[0].longitude)];                 ug = ug - gug;                 coordsarrrow[0].latitude  = ex;                 coordsarrrow[0].longitude = ey;                 coordsarrrow[1].latitude  = ex+lstr*cos(ug*m_pi/180);                 coordsarrrow[1].longitude = ey+lstr*sin(ug*m_pi/180);                 ug=ug+2*gug;                 coordsarrrow[2].latitude  = ex+lstr*cos(ug*m_pi/180);                 coordsarrrow[2].longitude = ey+lstr*sin(ug*m_pi/180);                  mkpolyline *points = [mkpolyline polylinewithcoordinates:coordsarrrow count:3];                 points.subtitle = @"arrow";                 [map addoverlay:points];                 break;             }         }         free(coordsarrrow);         currpoints1 = currpoints1 +14;     } 

oh guys. change other way. make annotation , rotate direction between 2 point.

metods :

calc direction:

     int currpoints1 = 2;     nslog(@"!!!!!!!!%d ",numpoints);     while(currpoints1 < numpoints)     {          trackpoint* current = nil;         cllocationcoordinate2d* coordsarrrow = malloc((2) * sizeof(cllocationcoordinate2d));         (int =currpoints1, j=0; < numpoints; i=i+1, j++)         {             current = [cashpoints objectatindex:i];             coordsarrrow[j] = current.coordinate;             if (i % 2 !=0) {                 directannotation *placemark=[[directannotation alloc] initwithcoordinate: coordsarrrow[0]];                  cllocationcoordinate2d coord1 = coordsarrrow[0];                 cllocationcoordinate2d coord2 = coordsarrrow[1];                  cllocationdegrees deltalong = coord2.longitude - coord1.longitude;                 cllocationdegrees ycomponent = sin(deltalong) * cos(coord2.latitude);                 cllocationdegrees xcomponent = (cos(coord1.latitude) * sin(coord2.latitude)) - (sin(coord1.latitude) * cos(coord2.latitude) * cos(deltalong));                  cllocationdegrees radians = atan2(ycomponent, xcomponent);                 cllocationdegrees degrees = radianstodegrees(radians) + 360;                  self.dir =  fmod(degrees, 360);                   nslog(@"%f,%f %f,%f",coordsarrrow[0].latitude,coordsarrrow[0].longitude,coordsarrrow[1].latitude,coordsarrrow[1].longitude);                 [self.map addannotation:placemark];                 break;             }         }         free(coordsarrrow);         currpoints1 = currpoints1 +14;     } 

and

annotation:

- (mkannotationview *)mapview:(mkmapview *)mv viewforannotation:(id <mkannotation>)annotation{   if ([annotation iskindofclass:[directannotation class]]) {     arrow=[[mkannotationview alloc] initwithannotation:annotation reuseidentifier:@"parkingloc"];     arrow.image = [uiimage imagenamed:@"userlocationcompass.png"];       cgaffinetransform transform = cgaffinetransformmakerotation(degreestoradians(dir));     arrow.transform = transform;      return arrow; }else {     return nil; }} 

but have problem
before zoom:

after zoom :

direction confused.