Swift for Beginners: Getting Started with iOS Development

Swift is Apple modern programming language for iOS, macOS, watchOS and tvOS development. Launched in 2014, it has become one of the most loved programming languages with a clean syntax and powerful features.

Swift Basics

// Variables and constants
var name = "John"          // mutable
let age = 25               // immutable (preferred)

// Type annotations
var score: Int = 0
var price: Double = 9.99
var isActive: Bool = true
var message: String = "Hello"

// String interpolation
let greeting = "Hello, \(name)! You are \(age) years old."

Optionals — Swift Key Feature

// Optional type - may or may not have a value
var email: String? = nil
email = "user@example.com"

// Safe unwrapping with if let
if let email = email {
    print("Email: \(email)")
} else {
    print("No email provided")
}

// Guard statement (preferred for early returns)
func sendEmail(to recipient: String?) {
    guard let email = recipient else {
        print("No email address")
        return
    }
    print("Sending to \(email)")
}

// Nil coalescing operator
let displayEmail = email ?? "Not provided"

// Optional chaining
let length = email?.count  // Returns Int? not Int

Closures

// Closure syntax
let multiply = { (a: Int, b: Int) -> Int in
    return a * b
}

// Trailing closure syntax
[1, 2, 3, 4, 5].filter { $0 > 2 }  // → [3, 4, 5]
[1, 2, 3].map { $0 * 2 }           // → [2, 4, 6]
[3, 1, 2].sorted { $0 < $1 }       // → [1, 2, 3]

Structs and Classes

// Struct (value type - preferred)
struct User {
    let id: String
    var name: String
    var email: String
    
    var initials: String {
        name.split(separator: " ")
            .compactMap { $0.first }
            .map { String($0) }
            .joined()
    }
    
    mutating func updateName(_ newName: String) {
        name = newName
    }
}

// Class (reference type)
class NetworkManager {
    static let shared = NetworkManager()
    private init() {}
    
    func fetchUser(id: String) async throws -> User {
        let url = URL(string: "https://api.example.com/users/\(id)")!
        let (data, _) = try await URLSession.shared.data(from: url)
        return try JSONDecoder().decode(User.self, from: data)
    }
}

SwiftUI — Modern iOS UI

import SwiftUI

struct ContentView: View {
    @State private var count = 0
    
    var body: some View {
        VStack(spacing: 20) {
            Text("Count: \(count)")
                .font(.largeTitle)
                .fontWeight(.bold)
            
            HStack {
                Button("−") { count -= 1 }
                    .buttonStyle(.bordered)
                Button("+") { count += 1 }
                    .buttonStyle(.borderedProminent)
            }
        }
        .padding()
    }
}