The formatting horrors you sometimes need to go through to fit Objective-C in a two column layout

gistfile1.m

- (NSURL *) writeImage:(NSImage *)image
  withSceneDocumentURL:(NSURL *)documentURL
      originalImageURL:(NSURL *)originalImageURL
{
    if (!originalImageURL) {
        // Let the default exporter write this image
        return nil;
    }
    NSString *sceneFileName =
      [documentURL lastPathComponent];
    NSString *documentName =
      [sceneFileName stringByDeletingPathExtension];
    NSURL *containerDirectory =
      [documentURL URLByDeletingLastPathComponent];
    // The name of the folder to store the images
    NSURL *imageFolder =
      [containerDirectory URLByAppendingPathComponent:
         [documentName stringByAppendingString:@"_textures"]];
  
    
    // Create the folder to put the images in
    NSError *folderCreationError = nil;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    BOOL folderCreationWasSuccessful =
      [fileManager createDirectoryAtURL:imageFolder
            withIntermediateDirectories:NO
                             attributes:nil
                                  error:&folderCreationError];
    // The documentation says that it's better to try and 
    // recover then to check for file existance
    if (!folderCreationWasSuccessful && 
        folderCreationError.code != NSFileWriteFileExistsError) {
        NSLog(@"Textures folder coudn't be created: %@",
              [folderCreationError localizedDescription]);
        return nil; // To signal that no image was saved
    }
    
    // Attempt to save the image
    NSString *imageName = [originalImageURL lastPathComponent];
    NSURL *imageURL =
      [imageFolder URLByAppendingPathComponent:imageName];

    NSData *imageData = [image TIFFRepresentation];
    BOOL savingImageWasSuccessful =
      [imageData writeToFile:[imageURL path]
                  atomically:YES];
    
    if (!savingImageWasSuccessful) {
        NSLog(@"Could not save image at URL: %@", 
             [imageURL absoluteString]);
        return nil; // To signal that no image was saved
    }
    
    return imageURL; // The URL of the saved image
}