StackClass.swift

import Foundation

class Stack<T: CustomStringConvertible>: CustomStringConvertible {
   
    private var array: [T] = []
    
    func pop() -> T? {
        let popItem = self.array.popLast()
        print("POP ITEM : \(popItem?.description ?? "")")
        return popItem
    }
   
    func peak() -> T? {
        if self.array.isEmpty { return nil }
        return self.array[self.array.count - 1]
    }
    
    func push(item: T) {
        print("PUSH ITEM : \(item.description)")
        array.append(item)
    }
    
    var isEmpty: Bool {
        return self.array.isEmpty
    }
    
    var count: Int {
        return self.array.count
    }
    
    var description: String {
        let top = "### STACK ###\n"
        let bottom = "\n#############\n"
        let elements = self.array.reversed().map { $0.description }.joined(separator: "\n")
        return top + elements + bottom
    }
    
}