SwiftGenerics.playground

import UIKit

protocol StackType {
    func example()
}

struct SimpleStack<T: StackType> {
    
    private var list:[T] = []
    
    mutating func push(item: T){
        list.append(item)
    }
    
    mutating func pop(){
        let lastElement = list.last
        lastElement?.example()
        list.removeLast()
    }
}

struct StackView: StackType {
    func example() {
        //Do something important
    }
}

var stack = SimpleStack<StackView>()
let view1 = StackView()
let view2 = StackView()

stack.push(item: view1)
stack.push(item: view2)


func swap<Element>(first: inout Element, second: inout Element){
    let tempFirst = first
    first = second
    second = tempFirst
}