Dictionary 谷歌地图api和苹果MKMapKit中的位置不同

我使用的是maps.googleapis.com/maps/api/directions/json？用于在objc中绘制路线。当我绘制直线时，坐标有轻微变化，这意味着接点和多段线不相交。有没有办法在MKMap中用精确的点进行绘图

我的代码

      NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/directions/json?origin=%f,%f&destination=%f,%f&sensor=false&mode=driving", agentLati, agentLogi, userLati, userLogi]];


..........

 if (polyLine !=nil) {
                [_route_Map removeOverlay:polyLine];
            }
            polyLine = [[MKPolyline alloc]init];
//            polyLine = [self polylineWithEncodedString:[[[[responseDict objectForKey:@"routes"] objectAtIndex:0]objectForKey:@"overview_polyline"] objectForKey:@"points"]];
               polyLine = [self polylineWithEncodedString:[[[[responseDict objectForKey:@"routes"] objectAtIndex:0]objectForKey:@"overview_polyline"] objectForKey:@"points"]];
            [_route_Map addOverlay:polyLine];