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Editorial Team
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Asked: 2026-06-14T08:07:20+00:00

I am trying to save an image to the camera roll. This actually used

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I am trying to save an image to the camera roll. This actually used to work wonderfully, but I had to work on other stuff and now I’m returning to the project to update it for iOS 6 and poof this feature no longer works at all on iOS6.

I have tried two approaches, both are failing silently without NSError objects. First, UIImageWriteToSavedPhotosAlbum:

UIImageWriteToSavedPhotosAlbum(img, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);

// Callback
-(void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    // error == nil
}

… and the ALAssetsLibrary approach:

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library writeImageToSavedPhotosAlbum:[img CGImage]
                          orientation:(ALAssetOrientation)[img imageOrientation]
                      completionBlock:^(NSURL *assetURL, NSError *error)
{
    // assetURL == nil
    // error == nil
}

Also, [ALAssetsLibrary authorizationStatus] == ALAuthorizationStatusAuthorized evaluates to true

On the Simulator, the app never shows up in the Settings > Privacy > Photos section, however on an actual iPad they do show that the app has permission to access photos. (Also, just to add: The first approach above was what I previously used – it worked on real devices & simulators alike, no problem).

I have also tried running this on the main thread to see if that changed anything – no difference. I was running it on the background previously and it used to work fine (on both simulator and device).

Can anyone shed some light?

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1 Answer

  1. Editorial Team

    Figured it out… I was doing something stupid. UIImage cannot take raw pixel data, you have to first massage it into a form it can accept, with the proper metadata.

    Part of the problem was that I was using Cocos2D to get a UIImage from a CCRenderTexture (getUIImageFromBuffer()) and when I switched to Cocos2D-x that function was no longer available, and I simply was ignorant to the fact that UIImage objects cannot be constructed with raw pixel data, I figured it handled header information & formatting automatically.

    This answer helped: iPhone – UIImage imageWithData returning nil

    And this example was also helpful:
    http://www.wmdeveloper.com/2010/09/create-bitmap-graphics-context-on.html?m=1

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