Apple filed the foldable iPhone in August 2014 US Patent No. 9,485,862 which was awarded 2 November 2016 by the United States Patent Office.
The phone uses “carbon nanotubes” (CN) which allow the phone to fold in half down the middle, and they claim that this technology resists cracking.
Samsung has also patented so many foldable phone designs.
Whether these phones actually appear on the market remains to be seen.