座標系変換

MapKitの座標系とUIViewの座標系の相互変換。

MapKitの座標系→UIViewの座標系

CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(latitude, longitude);
CGPoint point = [self.mapView convertCoordinate:coord toPointToView:self.mapView];

// point.x　　x軸
// point.y　　y軸

UIViewの座標系→MapKitの座標系

CGPoint point = [recognizer locationInView:self.view];
CLLocationCoordinate2D coord = [self.mapView convertPoint: point toCoordinateFromView:self.mapView];

// coord.latitude 緯度
// coord.longitude　経度

参考記事：
http://stackoverflow.com/questions/11252542/cgpoint-to-clllocationcoordinate2d-convertpoint-tocoordinatefromview-not-worki