Massive memory consumption with cocos2d sprite sheets

Question

Per the cocos2d best practices, I've packed my key assets for my game into 4 separate sprite sheets. FWIW, I created these sheets with TexturePacker and have crunched down the resultant .pngs with TinyPng. The largest sprite sheet of the 4 (which contains my dialogs) is 375KB large and 2048x2048px in the -hd variation (aka @2x).

I've been noticing memory issues in my game, so I booted up the Allocations tool in Instruments. Sure enough, the Main scene was using ~250MB of memory on retina devices (~95MB on non-retina devices). Woah! Huge! Even worse, there is fairly significant lag on older retina devices (e.g., the iPhone 4).

The first thing I did was to remove one of the sprite sheets, to see if this was the problem. Sure enough, simply not loading a single sprite sheet dropped retina memory by 60MB. Considering the sprite sheet in question is only 268KB in filesize, I'm shocked that this is such a big problem.

Here's the code I'm using to "preload" a sprite sheet (during the app startup):

- (BOOL)cacheSpriteSheet:(NSString*)sheetName 
{
    if(!sheetName) 
    {
        return NO;
    }
    NSString *fpSheet = [[AMAssetManager sharedManager] pathForSpriteSheet:sheetName];
    if(fpSheet) 
    {
        [[CCSpriteFrameCache sharedSpriteFrameCache] addSpriteFramesWithFile:fpSheet];
        return YES;
    }
    else 
    {
        Warn(@"NULL sheet for %@",sheetName);
        return NO;
    }
}

Question: why are my sprite sheets consuming so much memory, and how can I fix it?

Things I've tried so far:

[CCTexture2D setDefaultAlphaPixelFormat:kCCTexture2DPixelFormat_RGBA4444] helped to reduce memory footprint by ~20%, but I can only use it with some of the sprite sheets (others have, for example, radial gradients, which don't play nice).
[[CCSpriteFrameCache sharedSpriteFrameCache] removeUnusedSpriteFrames] doesn't seem to help (memory footprint remains the same)

YvesLeBorg YvesLeBorg · Accepted Answer · 2013-12-29T17:20:50

The file size has nothing to do with anything when it comes to 'in core' size. A pixel is a pixel is a pixel and most likely, each and every one of those 2048x2048 pixels take 32 bits. Your options are to :

split your sprite sheets, and load 'just in time' when you need the sprites.
Dont trust instruments when running on the simulator. To be certain, use

[[CCTextureCache sharedTextureCache] dumpCachedTextureInfo]

to know how much memory is really consumed by your sprites.

Memory allocations on simulator will give you very little useful indications. Build your release version, target a device, and monitor process size. That is more likely what will be the decisive factor before getting the dreaded memory warning.
Dont use instruments/simulator to gain any appreciation of performance and user experience. They lie. Use the lowliest device you plan to support with your app as the litmus test
Even if you remove unused sprite frames, if a single sprite frame (used) refers to a texture, it will still be retained.

Read this very interesting article to grasp textures vs memory and the required trade-offs.

Massive memory consumption with cocos2d sprite sheets

1 Answers