iOS Programming: The Big Nerd Ranch Guide (5th Edi   2. The Swift Language

About the 2. The Swift Language category (1)
Results of string interpolation: page 38 (3)
Help understanding if-let statement (5)
Quick Help showing nothing + error not showing in Playground (4)
Problem with statement in page 39 (Enumerations & Switch) (3)
How to read the underscore within prototype (2)