Thanks for your reply. I have seen this before and have used it store store Curve25519 private keys. I'm simply wanting to store a string value in KeyChain as a generic key type but am unable to work out how to do this.

Thank you for your your reply. Yes I know that using my phone as a simulator installs the app on my phone but as you say, the phone needs to be in Developer mode to run. I also know about TestFlight but was hoping to avoid all the red tape/paperwork :-) If you have a moment, how would I publish it as an unlisted app?