Swift Boolean Tutorial

Swift Bool

In Swift, Bool is a frozen structure, whose instances are either true or false.

In this tutorial, we will learn how to declare a Bool variable, how to initialize a variable with boolean value, different operations that can be done on boolean values, and how to use a boolean value with conditional statements.

Declare Boolean Variable

To declare a variable to be explicitly Bool, specify Bool keyword after the variable name during the declaration as shown in the following code snippet.

var b: Bool

Now, b is a variable that holds only boolean values.

We can also initialise the variable with a boolean value, of course either true or false.

var b = true

Now, b is a boolean value without any explicit declaration, because the first time we stored a value in the variable b is a boolean value.

Initialize Boolean Variable

To initialize a variable with boolean value, use assignment operator and assign true or false.

var a = true
var b = false

Logical Operations

Logical Operations transform one or more boolean values into a resulting boolean value.

Swift supports three Logical Operators. They are

Operator	Name	Description
!	Logical NOT Operator.	Takes a single operand and performs negation operation.
&&	Logical AND Operator.	Takes two operands and returns true only if both the operands are true, else false.
||	Logical OR Operator.	Takes two operands and returns true if at least one of the operands is true, else false.

In the following program, we take two Boolean variables, and perform Logical operations on them.

main.swift

var a = true
var b = false

print("!a is \(!a)")
print("a && b is \(a && b)")
print("a || b is \(a || b)")

Output

!a is false
a && b is false
a || b is true

Boolean Value in Conditional Statements

Boolean value is used to conditionally execute a set of statements in if, if-else, for loop, while loop, etc.

Conclusion

In this Swift Tutorial, we learned what Boolean is in swift, how to declare/initialize a boolean value, how to perform logical operations on boolean values, and how to use them with conditional statements, with the help of examples.