Arrays, sets, and tuples can seem similar at first, but they have distinct uses. To help you know which to use, here are some rules.
If you need a specific, fixed collection of related values where each item has a precise position or name, you should use a tuple:
let address = (house: 555, street: "Taylor Swift Avenue", city: "Nashville")
If you need a collection of values that must be unique or you need to be able to check whether a specific item is in there extremely quickly, you should use a set:
let set = Set(["aardvark", "astronaut", "azalea"])
If you need a collection of values that can contain duplicates, or the order of your items matters, you should use an array:
let pythons = ["Eric", "Graham", "John", "Michael", "Terry", "Terry"]
Arrays are by far the most common of the three types.