String literals

We surround a string literal with double quotes. In Swift a string literal can use string interpolation—a variable can be inserted into it.

We use the let keyword to declare these strings, as they are constants. To have a string that can be modified, please declare it with the var keyword (not let).

Combine strings

We can use the plus operator to combine two strings. This is also called concatenation. The resulting string is printed to the console.

// Two string literals.
let value = "cat "
let value2 = "and dog"

// Combine (concatenate) the two strings.
let value3 = value + value2
print(value3)
cat and dog

Append

A string that is declared with the var keyword can be appended to. A variable can be reassigned. Here we append to a string and use print to display it.

// This string can be changed.
var value = "one"

// Append data to the var string.
value += "...two"
print(value)
one...two

String interpolation

With this syntax we can insert variables (like Ints or other Strings) into a place in a String. No complex string operations are needed.

let name = "dotnetperls"
let id = 100

// Use string interpolation.
// ... Create a string with variable values in it.
let result = "Location: \(name), ID: \(id)"
print(result)
Location: dotnetperls, ID: 100

String literals are used in nearly every program. They are used in print statements. We use them to create text output in Swift.