In this video I am going to show you how to securely store user_id value into iOS Keychain and how to read it back. It is a very simple and very easy example and this is thanks to the open source project that I have came across recently. It is called SwiftKeychainWrapper
You can read more about iOS Keychain from Apple’s Keychain Services Programming Guide but I find it very technical and not very straightforward to understand if you are just starting with App Development for iOS Platform or have never dealt with iOS Keychain before.
Here is a video tutorial. I hope it is helpful to you.