Friends suggestions implementation

Friends.swift

import UIKit

// MARK: - Friends

class Person:Equatable{
    
    static func == (lhs: Person, rhs: Person) -> Bool {
        return lhs.name == rhs.name
    }
    
    var name:String
    var friends:[Person] //= []
    
    init(name:String) {
        self.name = name
        self.friends = []
    }
    
    func suggestFriends() -> [Person]?{
        
        var suggestions:[Person] = []
        var visited:[Person] = []
        
        var stack = friends
        
        while !stack.isEmpty {
            
            guard let next = stack.first else { return nil }
            
            // print("Next: \(next.name) + \(next.friends.count) friends")
            
            // Add (non-visited) persons to stack
            for person in next.friends.filter({$0 != self && !visited.contains($0)}){
                stack.append(person)
                visited.append(person)
            }
            
            // Suggest friend
            if !friends.contains(next){
                suggestions.append(next)
            }
            
            stack.removeFirst()
        }
        
        return suggestions
        
    }
}

var angie = Person(name: "Angie")
var betty = Person(name: "Betty")
var conrad = Person(name: "Conrad")
var dan = Person(name: "Dan")
var eva = Person(name: "Eva")
var fred = Person(name: "Fred")
var gabe = Person(name: "Gabe")
var helen = Person(name: "Helen")
var isabel = Person(name: "Isabel")

angie.friends = [betty, conrad]
betty.friends = [angie, conrad, dan]
conrad.friends = [angie, betty]
dan.friends = [betty, eva, fred]
eva.friends = [dan, helen, isabel]
fred.friends = [dan]
gabe.friends = [helen]
helen.friends = [isabel, eva, gabe]
isabel.friends = [helen, eva]

print("\n --- FRIENDS SUGGESTIONS ---\n")

let angiesSuggestions = angie.suggestFriends()
print("For Angie:")
for p in angiesSuggestions ?? []{
    print("\t Name: \(p.name) has \(p.friends.count) friends")
}
print("---")