Protocol Extensions

Prefer protocols with default implementations over base class inheritance. Protocol extensions provide shared behavior without coupling.

protocol Loadable {
    var isLoading: Bool { get set }
    func startLoading()
    func stopLoading()
}

extension Loadable {
    func startLoading() { /* default spinner logic */ }
    func stopLoading() { /* default cleanup */ }
}

Use protocol composition (Loadable & Cacheable) to combine capabilities without multiple inheritance problems.