Question

Now I have one trouble for develope one iPhone app.
I need to compute 150 parts and draw it on canvas.
I have code like this:

    for (int i=x1; i<=x2; i++) {
            for (int j=y1; j<=y2; j++) {
                    x=[NSNumber numberWithInt:i];
                    y=[NSNumber numberWithInt:j];

                    BoxCache *box = [[cache objectForKey:x] objectForKey:y];

                    if (box) {
                            ret.count += [box.species count];
                    }

                    [x release];
                    [y release];
            }
    }

His execution tired ~5 secs (computing array 15×10), I would like to ask everyone, any ideas to reduce compute time or do that different.

Answer 1

Instead of a dictionary of dictionaries (which is really inefficient), I’d use a regular old C array and malloc the memory myself. I might wrap it in a class just to make the memory management rules clearer, but that’s about it.