If and if-else statements in Swift

Introduction

If and if-else statements help your program make choices. They let your code do different things based on conditions.

To check if a number is positive or negative.

To decide what message to show based on user input.

To run some code only if a condition is true.

To choose between two actions depending on a test.

To handle simple decision-making in your app.

Syntax

Swift

if condition {
    // code to run if condition is true
} else {
    // code to run if condition is false
}

The condition must be a Boolean expression (true or false).

The else part is optional; you can use just if without else.

Examples

This checks if number is greater than zero and prints a message if true.

Swift

let number = 10
if number > 0 {
    print("Number is positive")
}

This prints "Positive" if number is above zero, otherwise it prints "Not positive".

Swift

let number = -5
if number > 0 {
    print("Positive")
} else {
    print("Not positive")
}

This decides voting eligibility based on age.

Swift

let age = 18
if age >= 18 {
    print("You can vote")
} else {
    print("You cannot vote yet")
}

Sample Program

This program checks the temperature and prints if it is hot or not.

Swift

let temperature = 30
if temperature > 25 {
    print("It's hot outside")
} else {
    print("It's not hot outside")
}

Important Notes

Always use curly braces { } even for single lines to avoid mistakes.

Conditions must be Boolean expressions, like comparisons (==, >, <).

Summary

If statements let your program choose actions based on conditions.

If-else statements provide two paths: one if true, another if false.

Use them to make your code respond to different situations.