These are the poorly written on purpose projects that go along with the talk "Practical iOS App Security"
The versions correspond to the back and forth between developer and security analyst over the ficticious app, "Keymaster". See slides here for more details:
SwiftSecureLang.playground is from the Swift portion of the talk.
V1 - User Defaults (yikes!)
V2 - Data Protection (but not good enough)
V3 - NSCoding and Plists instead of User Defaults
V4 - Core Data
V5 - Keychain and TouchID
V6 - The Apple Watch Edition!