Blackjack is an iOS app written in Swift that implements a basic game of blackjack. It targets iOS 13 but I don't think there is any reason it couldn't be made to target a lower version if you create an older Xcode project (without scenes). It uses UIKit and implements the UI programmatically other than the default initial setup.
Blackjack is licensed under the Unlicense. See the LICENSE file for more information, but basically this is sample code and you can do whatever you want with it.