**Course Title:** Swift Programming: From Basics to Advanced Development **Section Title:** Object-Oriented Programming (OOP) in Swift **Topic:** Create a class-based system demonstrating OOP principles.(Lab topic) **Introduction** Now that we have covered the basics of classes and structures in Swift, it's time to take our knowledge to the next level by creating a class-based system that demonstrates the principles of Object-Oriented Programming (OOP). In this lab, we will design and implement a simple banking system using classes and objects. **Understanding the Requirements** Before we dive into the implementation, let's define the requirements of our banking system: * We need to create a `Bank` class that has the following properties: name, address, and a list of accounts. * We need to create an `Account` class that has the following properties: account number, account holder's name, and balance. * We need to create a `Customer` class that has the following properties: name and address. * We need to implement methods to deposit, withdraw, and check the balance of an account. **Designing the Classes** Based on the requirements, we can design the following classes: ```swift // Customer class class Customer { var name: String var address: String init(name: String, address: String) { self.name = name self.address = address } } // Account class class Account { var accountNumber: Int var accountHolder: Customer var balance: Double init(accountNumber: Int, accountHolder: Customer, initialBalance: Double) { self.accountNumber = accountNumber self.accountHolder = accountHolder self.balance = initialBalance } func deposit(amount: Double) { balance += amount } func withdraw(amount: Double) { if balance >= amount { balance -= amount } else { print("Insufficient funds!") } } func checkBalance() -> Double { return balance } } // Bank class class Bank { var name: String var address: String var accounts: [Account] init(name: String, address: String) { self.name = name self.address = address self.accounts = [] } func addAccount(account: Account) { accounts.append(account) } func findAccount(accountNumber: Int) -> Account? { for account in accounts { if account.accountNumber == accountNumber { return account } } return nil } } ``` **Creating Objects and Using Methods** Now that we have defined the classes, let's create objects and use the methods to demonstrate the principles of OOP: ```swift // Create a bank object let bank = Bank(name: "Swift Bank", address: "123 Main St") // Create a customer object let customer = Customer(name: "John Doe", address: "456 Elm St") // Create an account object let account = Account(accountNumber: 1234, accountHolder: customer, initialBalance: 1000.0) // Add the account to the bank bank.addAccount(account: account) // Deposit money into the account account.deposit(amount: 500.0) // Withdraw money from the account account.withdraw(amount: 200.0) // Check the balance of the account print("Account balance: \(account.checkBalance())") // Find the account by account number if let foundAccount = bank.findAccount(accountNumber: 1234) { print("Account found: \(foundAccount.accountNumber)") } else { print("Account not found!") } ``` **Conclusion** In this lab, we have designed and implemented a class-based system that demonstrates the principles of Object-Oriented Programming (OOP) in Swift. We have created classes for `Customer`, `Account`, and `Bank`, and used methods to deposit, withdraw, and check the balance of an account. This lab demonstrates the power of OOP in creating reusable and modular code. **Key Takeaways** * Classes and objects are used to represent real-world entities and their properties. * Methods are used to perform actions on objects. * Inheritance, polymorphism, and encapsulation are key principles of OOP. * Swift's syntax and features make it an ideal language for OOP. **What's Next?** In the next topic, we will explore protocols and protocol-oriented programming in Swift. [Read more about protocols in Swift](https://docs.swift.org/swift-book/LanguageGuide/Protocols.html). **Leave a Comment or Ask for Help** If you have any questions or need help with this lab, please leave a comment below.