Architecture and Design System QnA

Architecture and Design System QnA.md

Architecture and Design System related QnA

SOLID Principle

The SOLID principles are 5 design principles used to write clean, maintainable, and scalable code.

1. S — Single Responsibility Principle (SRP)
   A class should have only one reason to change.
   → One class = one responsibility.

2. O — Open/Closed Principle (OCP)
   Code should be open for extension but closed for modification.
   → Add new behavior without changing existing code.

3. L — Liskov Substitution Principle (LSP)
   Subclasses should be replaceable for their parent classes without breaking behavior.
   → Child class must behave correctly as parent.

4. I — Interface Segregation Principle (ISP)
   Don’t force classes to implement methods they don’t need.
   → Create small, specific interfaces.

5. D — Dependency Inversion Principle (DIP)
   Depend on abstractions, not concrete implementations.
   → Use protocols/interfaces instead of direct class dependency.

Simple iOS Example

Instead of:

class NetworkManager {
    func fetch() {}
}

Prefer:

protocol Networking {
    func fetch()
}

class NetworkManager: Networking {
    func fetch() {}
}

class HomeViewModel {
    let network: Networking
    init(network: Networking) {
        self.network = network
    }
}

This follows DIP and improves testing & flexibility.