Swift Tutorial - Swift String

A string is a sequence of characters, such as "Hello World!".

Strings use the String data type, although you don't need to specify the data type to use a string.

var s1 = "Hello World!"

Unicode Characters

Strings can include any Unicode characters.

To write single-byte Unicode characters, you must include \x before the two hexadecimal digits.

Two-byte Unicode characters are prefixed with \u before four hexadecimal digits, and four-byte Unicode characters have \U written before eight hexadecimal digits.

The following code shows an example of using Unicode characters.

let percentage = "\x{25}"
let snowflake = "\u{2744}"
let heart = "\u{0001F497}"

Character Data Type

Strings are collections of characters, and characters have their own data type called Character.

Characters can have only one character, and you must explicitly declare your variable or constant as a Character.

The following code shows how to declare a Character type value.

let c1:Character = "A"


In Swift, you can combine strings and characters to create longer strings.

The following code shows how to create an alphabet string based on characters and strings.

//Declare characters and strings
let c1:Character = "A"
let c2:Character = "B"
let c3:Character = "C"
let c4:Character = "D"
let c5:Character = "E"
let s2 = "FGHIJ"

//Declare an empty string
var alphabet = String()

//Concatenate strings, characters and literals
alphabet = c1 + c2 + c3 + c4 + c5 + s2 + "KLMNOP"

Comparing Strings

We can compare two strings with comparison operator ==. It returns a boolean (true or false) value back.


String Interpolation

To print out different variables, constants, literals, and expressions in a string, use string interpolation.

String interpolation puts a forward slash \ in front of a variable name in parentheses.

let i:Int = -25
let f:Float = 3.14
let d:Double = 99.99
let b:Bool = true

println("i = \(i), f = \(f), d = \(d), b = \(b)")