What problem do design patterns help solve?.

Design patterns help solve common problems in software development by providing proven solutions that can be reused. They improve code reusability, readability, and maintainability. For example, the Singleton pattern ensures only one instance of a class exists, and the Observer pattern allows objects to subscribe to events and be notified of changes.

Example of Singleton pattern in Swift:

class Singleton {
    static let shared = Singleton()
    private init() { }

    func doSomething() {
        print("Singleton works")
    }
}

Singleton.shared.doSomething()