protocol_inheritance.swift

import UIKit


extension UIView: Showable {
    
}

protocol Showable {
    func layout()
    func animate() // Remove me to see the change
}

extension Showable where Self: UIView {
    func layout() {
        print("layout called from VIEW")
        animate()
    }
    
    func animate() {
        print("animate called from VIEW")
    }
}

extension Showable where Self: UIButton {
    func layout() {
        print("layout called from BUTTON")
        animate()
    }
    
    func animate() {
        print("animate called from BUTTON")
    }
    
}

let view = UIView()
view.layout()

let btn = UIButton()
btn.layout() // This one changes