How do you implement a stack data structure in your system?

A stack is a data structure that operates on the Last In, First Out (LIFO) principle. In Swift, a stack can be implemented using an array, adding push and pop methods to manage elements.

Example of a stack implementation in Swift:

struct Stack<Element> {
    private var elements: [Element] = []

    mutating func push(_ element: Element) {
        elements.append(element)
    }

    mutating func pop() -> Element? {
        return elements.popLast()
    }

    func peek() -> Element? {
        return elements.last
    }

    var isEmpty: Bool {
        return elements.isEmpty
    }

    var count: Int {
        return elements.count
    }
}

// Usage:
var stack = Stack<Int>()
stack.push(10)
stack.push(20)
print(stack.pop() ?? "empty") // 20
print(stack.peek() ?? "empty") // 10

This stack can be used for storing action history, navigation, and other tasks where the order of element processing is important.