How to dynamically create a 2d NSMutableArray with loops

问题

I made an original post here

At first, I tried to fill up a CGPoint **allPaths.

With the first dimension being "a path" and the second dimension being "the waypoint". And I get a CGPoint out of this.

For example : allPaths[0][2] would give me the CGPoint of the first path, third waypoint.

I successfully did it in plain C with nasty loops. And now I am trying to do the same thing in Obj-C with NSMutableArrays.

Here is my code :

CCTMXObjectGroup *path;
NSMutableDictionary *waypoint;

int pathCounter = 0;
int waypointCounter = 0;

NSMutableArray *allPaths = [[NSMutableArray alloc] init];
NSMutableArray *allWaypointsForAPath = [[NSMutableArray alloc] init];

//Get all the Paths
while ((path = [self.tileMap objectGroupNamed:[NSString stringWithFormat:@"Path%d", pathCounter]]))
{
    waypointCounter = 0;
    //Empty all the data of the waypoints (so I can reuse it)
    [allWaypointsForAPath removeAllObjects];

    //Get all the waypoints from the path
    while ((waypoint = [path objectNamed:[NSString stringWithFormat:@"Wpt%d", waypointCounter]]))
    {
        int x = [[waypoint valueForKey:@"x"] intValue];
        int y = [[waypoint valueForKey:@"y"] intValue];

        [allWaypointsForAPath addObject:[NSValue valueWithCGPoint:CGPointMake(x, y)]];
        //Get to the next waypoint
        waypointCounter++;
    }

    //Add the waypoints of the path to the list of paths
    [allPaths addObject:allWaypointsForAPath];

    //Get to the next path
    pathCounter++;
}

My actual problem is that all paths in allPaths are equal to the last one. (all the first paths are overrided with the last one)

I know that it is because of this line [allPaths addObject:allWaypointsForAPath].

Yet, how should I do it ?

回答1:

Oh I think I found out something ! Not sure about memory issue, but I guess the garbage collector should work ?

Actually, I just have to declaremy NSMutableArray *allWaypointsForAPath in the loop like this :

int pathCounter = 0;
int waypointCounter = 0;

NSMutableArray *allPaths = [[NSMutableArray alloc] init];

//Get all the PathZ
while ((path = [self.tileMap objectGroupNamed:[NSString stringWithFormat:@"Path%d", pathCounter]]))
{
    waypointCounter = 0;
    NSMutableArray *allWaypointsForAPath = [[NSMutableArray alloc] init];
    //Get all the waypoints from the path
    while ((waypoint = [path objectNamed:[NSString stringWithFormat:@"Wpt%d", waypointCounter]]))
    {
        int x = [[waypoint valueForKey:@"x"] intValue];
        int y = [[waypoint valueForKey:@"y"] intValue];
        [allWaypointsForAPath addObject:[NSValue valueWithCGPoint:CGPointMake(x, y)]];
        //Get to the next waypoint
        waypointCounter++;
    }

    [allPaths addObject:allWaypointsForAPath];
    //Get to the next path
    pathCounter++;
}

来源：https://stackoverflow.com/questions/11698682/how-to-dynamically-create-a-2d-nsmutablearray-with-loops

标签

ios

cocos2d-iphone

nsmutablearray