private MediaType guessTypeByExtension(Metadata metadata) {

        String fName = metadata.get(TikaCoreProperties.RESOURCE_NAME_KEY);
        if (fName == null) {
            return IWork13DocumentType.UNKNOWN13.getType();
        } else if (fName.toLowerCase(Locale.US).endsWith(".numbers")) {
            return IWork13DocumentType.NUMBERS13.getType();
        } else if (fName.toLowerCase(Locale.US).endsWith(".pages")) {
            return IWork13DocumentType.PAGES13.getType();
        } else if (fName.toLowerCase(Locale.US).endsWith(".key")) {
            return IWork13DocumentType.KEYNOTE13.getType();
        }
        return IWork13DocumentType.UNKNOWN13.getType();
    }
All iWork 13 files contain this, so we can detect based on it
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-apple-module/src/main/java/org/apache/tika/parser/iwork/iwana/IWork13PackageParser.java