Learn Swift 2 on the Mac, Second Edition

Chapter    6

Operators

General-purpose languages provide set of operators—convenience constructs that behave like functions—and Swift is no different. You’ve already seen at least one such operator: +. Swift provides a wide range of built-in operators and allows you to define operators for your own classes and to extend built-in classes to add new operators.

Syntax

Operators in Swift can be:

• Unary, which requires only one operand or input. (-a).
• Binary, which requires two operands or inputs. (a+b).
• Ternary, which requires three operands. (?:).

Notation

Operators come in one of three notations:

• Prefix, where the operator comes before the operand(s). The operator can be either unary or binary. (++a)
• Infix, where the operator requires two operands ...