CLLocationCoordinate2D without knowing how many will be in the array?

Question

I need to build an array using something like the following:

CLLocationCoordinate2D  points[4];


    points[0] = CLLocationCoordinate2DMake(41.000512, -109.050116);

    points[1] = CLLocationCoordinate2DMake(41.002371, -102.052066);

    points[2] = CLLocationCoordinate2DMake(36.993076, -102.041981);

    points[3] = CLLocationCoordinate2DMake(36.99892, -109.045267);

Problem is, I will never know how many items are going to be in the array, so I can specify the count. Is there a way to create a CLLocationCoordinate2D array, and just insert new coordinates without knowing what the final total will be?

EDIT: My final goal is to use the coordinates to make an MKPolyline, using the polylineWithCoordinates method which needs a CLLocationCoordinate2D array.

Bequeath

Answer 1

// unpacking an array of NSValues into memory
CLLocationCoordinate2D *points = malloc([mutablePoints count] * sizeof(CLLocationCoordinate2D));
for(int i = 0; i < [mutablePoints count]; i++) {
    [[mutablePoints objectAtIndex:i] getValue:(points + i)];
}

MKPolyline *myPolyline = [MKPolyline polylineWithCoordinates:points count:[mutablePoints count]];
free(points);

Senator

don't forget to add #include <stdlib.h> in that .m file AND, the function is sizeof(...) not size_of(...) ...just saved you 15 minutes. :D Otherwise worked great! – Indefensible

What actually happens here: CLLocationCoordinate2D *points = malloc([mutablePoints count] * sizeof(CLLocationCoordinate2D)); Would be great if someone could point this out. We aren't creating a C array aren't we? – Cords

We are indeed creating a C array. See the documentation for polylineWithCoordinates:count:. – Senator

what is mutablePoints? – Wince

@Wince it's just an NSArray. I was following up on Dave DeLong's answer. – Senator

Answer 2

Box them up in an NSValue object and throw them in an NSMutableArray.

Nephritis

But I am trying to create an MKPolyline from this using the polylineWithCoordinates method. – Bequeath

You'll have to unpack them from your NSMutableArray then into memory with some pointer math. – Senator