Understanding and implementing a BFS algorithm.

BFS.swift

class Node: CustomStringConvertible {
    var tagged: Bool
    var name: String = ""
    var subnodes: [Node] = []
    
    init(tagged: Bool, name: String = "") {
        self.tagged = tagged
        self.name = name
    }
    
    func add(_ node: Node) {
        subnodes.append(node)
    }
    
    func findTagged() -> Node? {
        var nodes = [Node](arrayLiteral: self)
        var i = 0
        repeat {
            let n = nodes[i]
            if n.tagged {
                return n
            }
            nodes.append(contentsOf: n.subnodes)
            i += 1
        } while i < nodes.count
        return nil
    }
    
    var description: String {
        return "\(name): \(tagged)"
    }
}

var root = Node(tagged: false, name: "root")

var sub1 = Node(tagged: false, name: "sub1")
var sub2 = Node(tagged: false, name: "sub2")
var subsub1 = Node(tagged: false, name: "subsub1")
var deep = Node(tagged: true, name: "deep")
subsub1.add(deep)
root.add(sub1)
sub2.add(subsub1)
root.add(sub2)

let tagged = root.findTagged()
print(tagged)