Mirror tree without recursion

tree.swift

class Node {
    var id = 0
    weak var parent: Node? = nil
    var left: Node? = nil {
        didSet {
            left?.parent = self
        }
    }
    var right: Node? = nil {
        didSet {
            right?.parent = self
        }
    }
}

func mirror(tree: Node) -> Node {
    let newTree = Node()

    var original: Node! = tree
    var mirrored: Node! = newTree

    while original != nil {
        mirrored.id = original.id

        if (original.left != nil) && (mirrored.right == nil) {
            original = original.left
            mirrored.right = Node()
            mirrored = mirrored.right
            continue
        }

        if (original.right != nil) && (mirrored.left == nil) {
            original = original.right
            mirrored.left = Node()
            mirrored = mirrored.left
            continue
        }

        original = original.parent
        mirrored = mirrored.parent
    }
    return newTree
}

var tree = Node()
tree.id = 0

tree.left = Node()
tree.left!.id = 1

tree.right = Node()
tree.right!.id = 2

tree.left!.left = Node()
tree.left!.left!.id = 3
tree.left!.right = Node()
tree.left!.right!.id = 4

//tree.right!.left = Node()
//tree.right!.left!.id = 5
tree.right!.right = Node()
tree.right!.right!.id = 6

tree.left!.left!.left = Node()
tree.left!.left!.left!.id = 7
tree.left!.left!.right = Node()
tree.left!.left!.right!.id = 8
tree.left!.right!.left = Node()
tree.left!.right!.left!.id = 9
tree.left!.right!.right = Node()
tree.left!.right!.right!.id = 10

//tree.right!.left!.left = Node()
//tree.right!.left!.left!.id = 11
//tree.right!.left!.right = Node()
//tree.right!.left!.right!.id = 12
tree.right!.right!.left = Node()
tree.right!.right!.left!.id = 13
tree.right!.right!.right = Node()
tree.right!.right!.right!.id = 14

extension Node: CustomStringConvertible {

    var indent: String {
        return "\t" + (parent?.indent ?? "")
    }

    var description: String {
        return "\(id)\n"
            + ( left != nil ? "\(indent)L:\(left!)" : "" )
            + ( right != nil ? "\(indent)R:\(right!)" : "" )
    }
}

print(tree)

print(mirror(tree))