**Course Title:** Swift Programming: From Basics to Advanced Development **Section Title:** Object-Oriented Programming (OOP) in Swift **Topic:** Defining classes and structures In this topic, we will explore the fundamentals of object-oriented programming (OOP) in Swift by learning how to define classes and structures. These are the building blocks of OOP, allowing us to create custom data types that encapsulate data and behavior. ### Classes and Structures: What's the Difference? In Swift, both classes and structures can be used to define custom data types. However, there are key differences between the two: * **Classes** are reference types, which means that when you assign a class instance to a new variable, both variables reference the same instance. Any changes made to the instance through one variable will affect the other variable as well. * **Structures**, on the other hand, are value types, which means that when you assign a structure instance to a new variable, a new copy of the instance is created. Any changes made to the instance through one variable will not affect the other variable. ### Defining a Class To define a class, you use the `class` keyword followed by the class name and a set of curly brackets `{}` that contain the class definition. ```swift class Person { // Class definition goes here } ``` Let's define a simple `Person` class with a `name` and `age` property: ```swift class Person { var name: String var age: Int init(name: String, age: Int) { self.name = name self.age = age } } ``` In this example, we've defined a `Person` class with `name` and `age` properties. We've also defined an initializer `init` that takes `name` and `age` parameters and assigns them to the corresponding properties. ### Defining a Structure To define a structure, you use the `struct` keyword followed by the structure name and a set of curly brackets `{}` that contain the structure definition. ```swift struct Coordinate { // Structure definition goes here } ``` Let's define a simple `Coordinate` structure with `x` and `y` properties: ```swift struct Coordinate { var x: Double var y: Double } ``` In this example, we've defined a `Coordinate` structure with `x` and `y` properties. Note that structures do not require an initializer, but you can define one if needed. ### Key Concepts * Classes are reference types, while structures are value types. * Classes are more flexible than structures and can be used to define complex data types with inheritance. * Structures are easier to use and require less boilerplate code than classes. ### Practical Takeaways * Use classes when you need to define a complex data type with inheritance. * Use structures when you need to define a simple data type with a small number of properties. ### Example Use Cases * Use a `Person` class to define a person with properties like `name`, `age`, and `address`. * Use a `Coordinate` structure to define a point in a 2D space with `x` and `y` properties. ### Additional Resources * [Swift Documentation: Classes and Structures](https://docs.swift.org/swift-book/LanguageGuide/ClassesAndStructures.html) * [Swift by Tutorials: Classes and Structures](https://www.raywenderlich.com/5815172-swift-classes-and-structures-tutorial) ### What's Next? In the next topic, we will explore properties and methods, initializers and deinitializers in Swift. You can ask questions or leave comments below if you have any questions or need further clarification. Please add your comment below if you have questions or need help on anything in this topic.