This chapter from Swift Programming: The Big Nerd Ranch Guide introduces conditionals in Swift, including if/else, ternary operator, nested ifs, and else if.
This chapter from Learning Swift 2 Programming, 2nd Edition covers the basic building blocks of Swift. It starts with variables and constants. With this knowledge, you will be able to store whatever you’d like in memory. This chapter also goes over how Swift handles loops and if/else statements.
This chapter from Learning Core Data for iOS with Swift: A Hands-On Guide to Building Core Data Applications, 2nd Edition shows how to add model versions and model mappings, and it demonstrates different migration techniques you can choose when upgrading a model.
Learning how to recognize and use optionals is an essential step in mastering the Swift language. This chapter from The Swift Developer's Cookbook introduces optionals and surveys the supporting constructs you need to create, test, and successfully use optionals in your code.