Tuples group multiple values into a single compound value. The values within a tuple can be of any type and do not have to be of the same type as each other.

Tuples are created by grouping any amount of values:

let tuple = ("one", 2, "three")

// Values are read using index numbers starting at zero
print(tuple.0) // one
print(tuple.1) // 2
print(tuple.2) // three

Also individual values can be named when the tuple is defined:

let namedTuple = (first: 1, middle: "dos", last: 3)

// Values can be read with the named property
print(namedTuple.first)  // 1
print(namedTuple.middle) // dos

// And still with the index number
print(namedTuple.2)      // 3

They can also be named when being used as a variable and even have the ability to have optional values inside:

var numbers: (optionalFirst: Int?, middle: String, last: Int)?

//Later On
numbers = (nil, "dos", 3)

print(numbers.optionalFirst)// nil
print(numbers.middle)//"dos"
print(numbers.last)//3

Tuples can be decomposed into individual variables with the following syntax:

let myTuple = (name: "Some Name", age: 26)
let (first, second) = myTuple

print(first) // "Some Name"
print(second)  // 26

This syntax can be used regardless of if the tuple has unnamed properties:

let unnamedTuple = ("uno", "dos")
let (one, two) = unnamedTuple
print(one) // "uno"
print(two) // "dos"

Specific properties can be ignored by using underscore (_):

let longTuple = ("ichi", "ni", "san")
let (_, _, third) = longTuple
print(third) // "san"

Functions can return tuples:

func tupleReturner() -> (Int, String) {
    return (3, "Hello")
}

let myTuple = tupleReturner()
print(myTuple.0) // 3
print(myTuple.1) // "Hello"

If you assign parameter names, they can be used from the return value:

func tupleReturner() -> (anInteger: Int, aString: String) {
    return (3, "Hello")
}

let myTuple = tupleReturner()
print(myTuple.anInteger) // 3
print(myTuple.aString) // "Hello"

Occasionally you may want to use the same tuple type in multiple places throughout your code. This can quickly get messy, especially if your tuple is complex:

// Define a circle tuple by its center point and radius
let unitCircle: (center: (x: CGFloat, y: CGFloat), radius: CGFloat) = ((0.0, 0.0), 1.0)

func doubleRadius(ofCircle circle: (center: (x: CGFloat, y: CGFloat), radius: CGFloat)) -> (center: (x: CGFloat, y: CGFloat), radius: CGFloat) {
    return (circle.center, circle.radius * 2.0)
}

If you use a certain tuple type in more than one place, you can use the typealias keyword to name your tuple type.

// Define a circle tuple by its center point and radius
typealias Circle = (center: (x: CGFloat, y: CGFloat), radius: CGFloat)

let unitCircle: Circle = ((0.0, 0.0), 1)

func doubleRadius(ofCircle circle: Circle) -> Circle {
    // Aliased tuples also have access to value labels in the original tuple type.
    return (circle.center, circle.radius * 2.0)
}

If you find yourself doing this too often, however, you should consider using a struct instead.

Tuples are useful to swap values between 2 (or more) variables without using temporary variables.

Example with 2 variables

Given 2 variables

var a = "Marty McFly"
var b = "Emmett Brown"

we can easily swap the values

(a, b) = (b, a)

Result:

print(a) // "Emmett Brown" 
print(b) // "Marty McFly"

Example with 4 variables

var a = 0
var b = 1
var c = 2
var d = 3

(a, b, c, d) = (d, c, b, a)

print(a, b, c, d) // 3, 2, 1, 0

Use tuples in a switch

let switchTuple = (firstCase: true, secondCase: false)
   
switch switchTuple {   
 case (true, false):
    // do something
 case (true, true):
    // do something
 case (false, true):
    // do something
 case (false, false):
    // do something
}

Or in combination with an Enum For example with Size Classes:

    let switchTuple = (UIUserInterfaceSizeClass.Compact, UIUserInterfaceSizeClass.Regular)
    
    switch switchTuple {
    case (.Regular, .Compact):
        //statement
    case (.Regular, .Regular):
        //statement
    case (.Compact, .Regular):
        //statement
    case (.Compact, .Compact):
        //statement
    }