UIImageWriteToSavedPhotosAlbum saves only 5 image out of 10. Why?

I have the problem as the title goes. Are there any restrictions, like "Export only 3 image开发者_开发技巧 per second", or something like?

        for (int frameStepper = 0; frameStepper < [Something frameCount]; frameStepper++)
        {
            //Get the filename.
            imagePath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"frame_%i.jpg", frameStepper]];

            //Read image.
            UIImage *image = [[[UIImage alloc] initWithContentsOfFile:imagePath] autorelease];

            //Write image.
            UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
        }

I have 5 images exported out of 10 after this code. Cannot see why. Please help, many thanks.

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A variation of this helped me: http://iphoneincubator.com/blog/tag/uiimagewritetosavedphotosalbum

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

}


- (void)imageSavedToPhotosAlbum:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {
    if (error) {
        [self tryWriteAgain:image];
    }
}

-(void)tryWriteAgain:(UIImage *)image
{
    UIImageWriteToSavedPhotosAlbum(image, self, @selector(imageSavedToPhotosAlbum: didFinishSavingWithError: contextInfo:), nil);
}

---

If I log the error of completion, it says:

Error Domain=ALAssetsLibraryErrorDomain Code=-3301 "Write busy" UserInfo=0x69e8e20 {NSLocalizedFailureReason=There was a problem writing this asset because the writing resources are busy., NSLocalizedRecoverySuggestion=Try to write again, NSLocalizedDescription=Write busy}

That means I have to wait for the completition of the running processes by implementing the given callback:

- (void)               image: (UIImage *) image
    didFinishSavingWithError: (NSError *) error
                 contextInfo: (void *) contextInfo

Hurray.