Swift: Type Aliases, Booleans, Tuples

Type Aliases

Type aliases are a way to give a new name to an existing type. This can be useful for making your code more readable and understandable.

To create a type alias, use the typealias keyword. The syntax is as follows:

typealias NewTypeName = ExistingTypeName

For example, the following code creates a type alias called Distance for the Double type:
typealias Distance = Double

Once you have created a type alias, you can use it anywhere you would use the existing type. For example, the following code declares a variable of type Distance:
var distance: Distance = 10.0

Booleans

Booleans are a special type of value that can be either true or false.

Booleans are often used in conditional statements, such as if and while statements. For example, the following code uses a boolean to control the flow of the program:

let isLoggedIn = true

if isLoggedIn {
  // The user is logged in.
} else {
  // The user is not logged in.
}

Tuples

Tuples are a way to group together values of different types.

To create a tuple, use the ( and ) symbols. The syntax is as follows:
(value1, value2, ...)

For example, the following code creates a tuple containing a name and an age:
let person = ("Alice", 25)

Once you have created a tuple, you can access the individual values in the tuple using their index. For example, the following code accesses the name and age from the person tuple:

let name = person.0
let age = person.1
Tuples can also be used to return multiple values from a function. For example, the following function returns a tuple containing the sum and difference of two numbers:

func addAndSubtract(number1: Int, number2: Int) -> (Int, Int) 
{ 
 let sum = number1 + number2 
 let difference = number1 - number2 
 return (sum, difference) 
}

The following code shows how to use the addAndSubtract() function:

let result = addAndSubtract(number1: 10, number2: 5) 
let sum = result.0 
let difference = result.1 
print("The sum is \(sum).") 
print("The difference is \(difference).")

Previous: Swift: Type Safety and Conversions       Next: Optionals, nil, Optional Binding
iOS Developer since 2015

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