Understanding Swift Else if Statement

Introduction

In Swift, an if statement can be extended with optional else if and else clauses to handle multiple conditions sequentially. This structure allows for precise decision-making based on different conditions.

The if...else if...else construct forms a decision tree where each condition is checked in order. The first condition that evaluates to true will execute its corresponding block of code. If none of the conditions are met, the else block executes.

This structure is also commonly referred to as the if-else ladder.

Key Points to Remember

An if statement can have zero or one else clause, which must appear after all else if clauses.
An if statement can have zero to many else if clauses, which must precede the else clause.
Once an else if condition is met, subsequent else if and else blocks are ignored.

Syntax

if condition1 {
// Executes when condition1 is true
} else if condition2 {
// Executes when condition2 is true
} else if condition3 {
// Executes when condition3 is true
} else {
// Executes when none of the above conditions are met
}

Example 1: Checking an Integer Value

Let's demonstrate how to use an if...else if...else statement in Swift.

import Foundation

var value: Int = 42

if value < 10 {
print("Value is less than 10")
} else if value < 50 {
print("Value is between 10 and 49")
} else {
print("Value is 50 or greater")
}

print("Final value: \(value)")

Output

Value is between 10 and 49
Final value: 42

Example 2: Determining the Type of a Number

import Foundation

let number = -5

if number > 0 {
print("Positive number")
} else if number < 0 {
print("Negative number")
} else {
print("Number is zero")
}

Output

Negative number

Example 3: Categorizing an Age Group

import Foundation

let age = 25

if age < 13 {
print("Child")
} else if age < 20 {
print("Teenager")
} else if age < 60 {
print("Adult")
} else {
print("Senior")
}

Output

Adult