Implemented Stack Data Structure with/without Generics

Generics_Stack_Implementation

//Without using generics
struct StackEx {
    private var items: [Any] = []
    mutating func push(item: Any) { items.append(item) }
    mutating func pop() -> Any { items.popLast() as Any }
    var top: Any { return items.last as Any }
    mutating func getAll() -> [Any] { return items }
}

var stacktEx = StackEx()
stacktEx.push(item: 10); stacktEx.push(item: 11); stacktEx.push(item: 12)
stacktEx.getAll()
stacktEx.pop()
stacktEx.getAll()
stacktEx.top


// Using Generic.
struct GenericStack<ItemType> {
    private var items: [ItemType] = []
    mutating func push(item: ItemType) { items.append(item) }
    mutating func pop() { items.popLast() }
    var top: ItemType? { return items.last }
    mutating func getAll() -> [ItemType]?  { return items }
}

var intStack = GenericStack<Int>()
intStack.push(item: 10); intStack.push(item: 11); intStack.push(item: 12); intStack.push(item: 13)
intStack.getAll()
intStack.pop()
intStack.getAll()
intStack.top

var strStack = GenericStack<String>()
strStack.push(item: "a"); strStack.push(item: "b"); strStack.push(item: "c")
strStack.getAll()
strStack.pop()
strStack.getAll()
strStack.top