gistfile1.txt

BOOL noError(NSError **error) {
    return (error && [*error code] == 0);
}

BOOL hasError(NSError **error) {
    return !noError(error);
}

BOOL deleteFileAtPath(NSString *path, NSError **error) {
    BOOL success = [[NSFileManager defaultManager] removeItemAtPath:path error:error];
    //If we failed because the file or directory didn't exist this is ok. Proceed as if successful.
    if (!success && noSuchFileOrDirectoryError(error)) return YES;
    return (success && noError(error));
}

BOOL cleanDirectories(NSArray *directories, NSError **error) {
    for(NSString *directory in directories) {
        [[NSFileManager defaultManager] createDirectoryAtPath:directory
                                  withIntermediateDirectories:YES
                                                   attributes:nil
                                                        error:error];
    }
    
    if (noError(error)) {
        for(NSString *directory in directories) {
            NSArray *files = existingFileNamesInDirectory(directory, error);
            for(NSString *fileName in files) {
                if (!deleteFileAtPath([directory stringByAppendingPathComponent:fileName], error)) break;
            }
            if (hasError(error)) break;
        }
    }
    
    return noError(error);
}