Mapkit overlay starting coordinate from Random coordinate - ios

Question

In my app I'm drawing the polyline overlay on the map with the points starting from the user Locations obtained from the didUpdateUserLocation: delegate method.
But for some reason it always starts from Africa.
What could be the reason? Do I have to specify any starting coordinate for the polyline?
-(void)drawTheRoute{
[self.mapViewTrace removeOverlay:self.polyline];
CLLocationCoordinate2D coordinates[arrayOfPoint.count];
int i = 1;
for (TMPoint *point in arrayOfPoint) {
coordinates[i] = point.coordinate;
i++;
}
MKPolyline *polyline = [MKPolyline polylineWithCoordinates:coordinates count:arrayOfPoint.count];
[self.mapViewTrace addOverlay:polyline];
self.polyline = polyline;
self.lineRenderer = [[MKPolylineRenderer alloc] initWithPolyline:self.polyline];
self.lineRenderer.strokeColor = [UIColor redColor];
self.lineRenderer.lineWidth = 5;
}
- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation{
TMPoint *point = [[TMPoint alloc] initWithCoordinate:userLocation.location.coordinate withSpeed:userLocation.location.speed];
[arrayOfPoint addObject:point];
[self drawTheRoute];
}

Answer 1

In the drawTheRoute method, the C array coordinates is declared with arrayOfPoint.count elements and the for loop initializes each index of the C array using i as the index variable.
The problem is that the i index variable is initially set to 1 instead of 0.
The first index of a C array (and NSArrays) is index 0 -- not 1.
This leaves the first coordinate of coordinates as uninitialized and the memory happened to contain values that were interpreted as the coordinate 0, 0 (and sometimes "random" coordinates).
(The other effect is that when arrayOfPoint has only one object, the C array will only have one element with an index of 0. But since i is initialized to 1, the for loop will end up setting index 1 (the second element) of the C array even though only one element of memory was allocated and you will be accessing memory not allocated to you which could result in EXC_BAD_ACCESS.)
Change this line:
int i = 1;
to this:
int i = 0;