Simple Hash Table implementation in Swift. Includes Linked List, and Node structures. Basic methods.

HashTable.swift

struct HashTable<Key: Hashable, Value> {
    private typealias Element = (key: Key, value: Value)
    private typealias List = LinkedList<Element>
    
    private var table: [List]
    
    init(size: Int) {
        table = Array<List>()
        
        for _ in 0..<size {
            let list = List()
            table += [list]
        }
    }
    
    func value(forKey key: Key) -> Value? {
        let index = self.index(forKey: key)
        var node = table[index].head
        
        while node != nil {
            if node!.data.key == key {
                return node!.data.value
            }
            node = node!.next
        }
        
        return nil
    }
    
    mutating func append(_ value: Value, forKey key: Key) {
        let index = self.index(forKey: key)
        table[index].append((key: key, value: value))
    }
    
    func index(forKey key: Key) -> Int {
        return abs(key.hashValue % table.count)
    }
}

LinkedList.swift

class LinkedList<Element> {
    var head: Node<Element>?
    var tail: Node<Element>?
    
    func append(_ element: Element) {
        let node = Node(element)
        
        if tail != nil {
            tail!.next = node
        } else {
            head = node
        }
        
        tail = node
    }
}

Node.swift

class Node<Element> {
    var data: Element
    var next: Node<Element>?
    
    init(_ data: Element) {
        self.data = data
    }
}