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Asked: 2026-05-11T13:12:46+00:00

I’m using UIImage to render a game map from 32×32 blocks. The code is

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I’m using UIImage to render a game map from 32×32 blocks. The code is as follows

for( int x = 0; x < rwidth; ++x) {     for(int y = 0; y < rheight; ++y)     {         int bindex = [current_map GetTileIndex:x :y];         CGPoint p;         p.x = x * tile_size_x;         p.y = y * tile_size_x;         [img_list[bindex] drawAtPoint:p];     } }

This ends up rendering about 150 tiles. My problem is when I run this code my render time goes down to 2-3 frames a second.

I thought the iPhone was fill bound, however if I force bindex to = 1 (ie render the same block 150 times) then I get full framerate.

I can’t believe it is that expensive to render from different UIImages.

Could someone please tell me what I’m doing wrong …

Oh I forgot to mention my image list created from a bigger texture page using CGImageCreateWithImageInRect.

Thanks Rich

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1 Answer

  1. Crack open Instruments and profile your code. It looks like you are drawing into a UIView, and they are not really optimized for games.. Since UIViews are layer-backed, drawAtPoint: needs to draw the image several times (to offscreen buffers) before it appears on screen.

    That being said, UIImage isn’t really designed for games. There’s a lot of overhead with regards to being part of UIKit. You’re not really meant to have hundreds of them.

    In approx order of speed (slowest to fastest):

    • UIImage (usually used if you have a few large images)
    • CALayers (if you need fine animation control or you have roughly 20 to 100 tiles/images)
    • OpelGL textures (what most games should be using)
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