If you want to build iOS apps for iPhone and iPad, learning Swift programming is your first step. Swift is modern, powerful, and beginner-friendly.

In this guide, we will cover:

• What is Swift
• Variables & Constants
• Data Types
• Conditionals (if/else, switch)
• Loops
• Functions
• Optionals (Very Important)
• Struct vs Class
• OOP Concepts in Swift

Let’s begin 🚀

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What is Swift?

Swift is a powerful and intuitive programming language developed by Apple Inc. in 2014 for building apps for:

• iOS
• iPadOS
• macOS
• watchOS
• tvOS

Swift is:

• Safe (prevents common coding errors)
• Fast (high performance)
• Modern syntax
• Easy to read and write

It replaced Objective-C as the primary language for iOS development.

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Variables & Constants in Swift

In Swift, we use:

• var → for variables (can change value)
• let → for constants (cannot change value)

Example:

var name = "Saktidatt"
let country = "India"name = "John"   // Allowed
// country = "USA" ❌ Error (cannot change constant)

💡 Best practice: Always use let unless the value needs to change.

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Data Types in Swift

Swift is a strongly typed language.

Common Data Types:

Type	Example
String	"Hello"
Int	10
Double	10.5
Float	3.14
Bool	true or false

Example:

let age: Int = 30
let price: Double = 199.99
let isLoggedIn: Bool = true

Swift can also infer types automatically:

let city = "Bhubaneswar"   // Swift understands this is String

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Conditionals in Swift

Conditionals help you execute code based on conditions.

1️⃣ if / else

let age = 18if age >= 18 {
    print("You are eligible to vote")
} else {
    print("You are not eligible")
}

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2️⃣ switch Statement

Swift’s switch is powerful and does NOT require break.

let grade = "A"switch grade {
case "A":
    print("Excellent")
case "B":
    print("Good")
default:
    print("Keep Improving")
}

---

Loops in Swift

Loops help repeat code execution.

1️⃣ for-in Loop

for i in 1...5 {
    print(i)
}

Output:

1 2 3 4 5

---

2️⃣ while Loop

var number = 1while number <= 5 {
    print(number)
    number += 1
}

---

Functions in Swift

Functions help organize reusable code.

Basic Function Example

func greet(name: String) {
    print("Hello \(name)")
}greet(name: "Saktidatt")

---

Function with Return Value

func add(a: Int, b: Int) -> Int {
    return a + b
}let result = add(a: 10, b: 20)
print(result)

---

Optionals in Swift (Very Important Topic ⚠️)

Optionals are one of the most important features in Swift.

An optional means:
👉 A variable may have a value OR it may be nil.

Declaring Optional

var middleName: String?

This means middleName can contain:

• A String
• OR nil

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Why Optionals Matter?

Swift prevents null pointer exceptions using optionals.

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1️⃣ Force Unwrapping (Not Recommended)

var name: String? = "John"
print(name!)

⚠️ If name is nil → app crashes.

---

2️⃣ Safe Unwrapping using if let (Recommended)

var name: String? = "John"if let safeName = name {
    print(safeName)
}

---

3️⃣ Guard Let (Best Practice in Functions)

func printName(name: String?) {
    guard let safeName = name else {
        print("Name is nil")
        return
    }
    
    print(safeName)
}

---

Struct vs Class in Swift

This is a very important interview topic.

Struct

struct Person {
    var name: String
    var age: Int
}

Class

class Employee {
    var name: String
    var salary: Double
    
    init(name: String, salary: Double) {
        self.name = name
        self.salary = salary
    }
}

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Key Differences

Struct	Class
Value Type	Reference Type
Stored in Stack	Stored in Heap
No Inheritance	Supports Inheritance
Faster	Slightly slower

Example Difference

struct Car {
    var name: String
}var car1 = Car(name: "BMW")
var car2 = car1
car2.name = "Audi"print(car1.name) // BMW (Original not changed)

With class, original object would change because it’s reference type.

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OOP Concepts in Swift

Swift fully supports Object-Oriented Programming.

1️⃣ Encapsulation

class BankAccount {
    private var balance: Double = 0
    
    func deposit(amount: Double) {
        balance += amount
    }
    
    func getBalance() -> Double {
        return balance
    }
}

---

2️⃣ Inheritance

class Animal {
    func makeSound() {
        print("Some sound")
    }
}class Dog: Animal {
    override func makeSound() {
        print("Bark")
    }
}

---

3️⃣ Polymorphism

let animal: Animal = Dog()
animal.makeSound()  // Bark

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4️⃣ Abstraction

Using protocols:

protocol Vehicle {
    func start()
}class Bike: Vehicle {
    func start() {
        print("Bike started")
    }
}

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Final Thoughts

Swift is:

• Beginner friendly
• Powerful
• Safe
• Industry standard for iOS development

If you’re planning to become an iOS developer in 2026, mastering these Swift basics is mandatory before moving to:

• UIKit
• SwiftUI
• MVVM
• Clean Architecture
• Networking
• Concurrency