Dead simple Swift queue implementation. Let’s put ARC to work. It’s here anyways.

Queue.swift

public class Queue<Element> {
    private class QueueItem {
        let value: Element
        var next: QueueItem?

        init(_ value: Element) {
            self.value = value
        }
    }

    private var front: QueueItem?
    private weak var back: QueueItem?

    public var isEmpty: Bool {
        return front == nil
    }

    public init() {}

    /// Add a new item to the back of the queue.
    public func enqueue(_ value: Element) {
        let item = QueueItem(value)
        if let back = back {
            back.next = item
        } else {
            front = item
        }
        back = item
    }

    /// Return and remove the item at the front of the queue.
    public func dequeue() -> Element? {
        guard let dequeued = front else { return nil }
        front = dequeued.next
        return dequeued.value
    }

    public func removeAll() {
        front = nil
    }
}