What design patterns have you applied in your programming practice?

In iOS development, I often use the following design patterns:

• MVC (Model-View-Controller) — a classic pattern for separating application logic, presentation, and data.
• MVVM (Model-View-ViewModel) — helps to separate presentation logic from UI, often used together with RxSwift or Combine.
• Delegate — widely used for passing events between objects, for example, UITableViewDelegate.
• Singleton — for creating a single instance of a class, such as a settings or session manager.
• Factory — for creating objects with different configurations without exposing the creation logic.

Example of using a delegate:

protocol MyDelegate: AnyObject {
    func didUpdateData()
}

class DataManager {
    weak var delegate: MyDelegate?
    func fetchData() {
        // data loading
        delegate?.didUpdateData()
    }
}