String interpolation is a way to construct new strings that contain constants, variables, literals, and expressions. Each entry of the string literal you inserted is wrapped in parentheses prefixed by a backslash:
let x = 3 let str = "\(x) * 5 = \(Double(x) * 5)" print(str)
Below is above code execution result.
3 * 5 = 15.0
In the example above, x is inserted as \(x) into a literal string. This placeholder is replaced with the actual value of x when the string is created for interpolation.
The value of x is also part of the following expression in the string. This expression evaluate
Double(x) * 5 and inserts the result (15) into the string.
Please note : Expressions written in parentheses in interpolation strings can not contain unescaped double quotes (“) and backslash (\), and can not contain enter or new line characters.