30 Days of SwiftUI - Day 3: Mastering Conditions and Loops in Swift

March 17, 2025

Introduction

Today's focus is on conditions and loops — vital tools that control your app's flow and behavior. Mastering these concepts will make your SwiftUI apps more dynamic and powerful. Let's dive in!

How to Check a Condition is True or False

Conditional statements like if let you check whether a condition is true or false.

Example:

let isRaining = true
if isRaining {
    print("Take an umbrella!")
} else {
    print("Enjoy the sunshine!")
}

How Does Swift Let Us Compare Many Types of Data?

Swift allows comparisons between integers, strings, and even tuples with its comparison operators (==, !=, <, >, <=, >=).

Example:

if "Apple" < "Banana" {
    print("Apple comes before Banana")
}

if (5, "Hello") < (5, "World") {
    print("Swift compares elements one by one")
}

How to Check Multiple Conditions

For more complex conditions, use && (AND) and || (OR).

Example:

let isSunny = true
let isWeekend = true

if isSunny && isWeekend {
    print("Perfect day for a picnic!")
} else if isSunny || isWeekend {
    print("At least one good condition!")
} else {
    print("Might want to stay indoors.")
}

Combining Conditions

Swift allows combining multiple conditions for concise checks.

Example:

let age = 25
let hasTicket = true

if age >= 18 && hasTicket {
    print("You may enter.")
} else {
    print("Entry denied.")
}

How to Use Switch Statements to Check Multiple Conditions

The switch statement is great for checking multiple cases efficiently.

Example:

let dayOfWeek = "Monday"

switch dayOfWeek {
case "Monday":
    print("Start of the week!")
case "Friday":
    print("Weekend vibes loading...")
case "Saturday", "Sunday":
    print("It's weekend time!")
default:
    print("It's a regular weekday.")
}

How to Use Switch Statements with Enums

Switch statements work seamlessly with enums, improving code clarity and reducing errors.

Example:

enum Weather {
    case sunny, rainy, cloudy, windy
}

let todayWeather = Weather.sunny

switch todayWeather {
case .sunny:
    print("It's a bright day!")
case .rainy:
    print("Don't forget an umbrella!")
case .cloudy, .windy:
    print("Mild weather today.")
}

When Should You Use Switch Statements Rather Than If?

Use if for simple conditions.
Use switch when there are multiple distinct cases, especially when handling enums.

How to Use the Ternary Conditional Operator for Quick Tests

The ternary operator is a compact way to perform quick conditions.

Example:

let score = 85
let result = score >= 60 ? "Pass" : "Fail"
print(result) // Output: Pass

This shorthand improves readability for simple conditions.

How to Use a For Loop to Repeat Work

for loops are ideal for iterating over collections or repeating tasks a set number of times.

Example:

for number in 1...5 {
    print("Counting: \(number)")
}

Use of Underscores with Loops

If the loop index isn’t required, use _ to ignore it.

Example:

for _ in 1...3 {
    print("SwiftUI is awesome!")
}

Why Does Swift Have Two Range Operators?

... (Closed range) includes the final value: 1...5 includes 5.
..< (Half-open range) excludes the final value: 1..<5 stops at 4.

Example:

for number in 1...5 { print(number) } // Output: 1 to 5
for number in 1..<5 { print(number) } // Output: 1 to 4

How to Use a While Loop to Repeat Work

while loops continue running as long as the condition is true.

Example:

var countdown = 5
while countdown > 0 {
    print("Countdown: \(countdown)")
    countdown -= 1
}
print("Blast off!")

When Should You Use a While Loop?

Use while for indefinite loops where the number of iterations isn’t known beforehand.
For example, waiting for a user to log in or network data to arrive.

How to Skip Loop Items with `break` and `continue`

break: Exits the loop entirely.
continue: Skips the current iteration and moves to the next one.

Example:

for number in 1...10 {
    if number == 3 {
        continue // Skips number 3
    }
    if number == 8 {
        break // Stops the loop at 8
    }
    print(number)
}

Output:

When to Use `break` and When to Use `continue`

Use break to exit loops early when further iterations are unnecessary.
Use continue when you only need to skip specific iterations without ending the loop.

Summary: Conditions and Loops

Today, we explored essential programming concepts like if statements, switch cases, ternary operators, and different types of loops. Mastering these tools will enable you to build logic-driven SwiftUI apps efficiently!

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