ViewController.swift

class ViewController: UIViewController, UITextFieldDelegate {

    private weak var tableView: UITableView!
    private weak var textField: UITextField!

    private lazy var throttle: Throttle<String> = Throttle(timeout: 0.3) { (query) in
        self.runFetch(query)
    }
    private let switcher = SwitchToLatest()

    private var results = [String]() {
        didSet {
            tableView.reloadData()
        }
    }

    private var currentText = "" {
        didSet {
            if currentText.characters.count < 4 {
                throttle.cancel()
            }
            else {
                throttle.input(currentText)
            }
        }
    }

    override func viewDidLoad() {

        textField.delegate = self
    }

    func textDidChange(sender: AnyObject) {

        if currentText != textField.text {
            currentText = textField.text!
        }
    }

    private func runFetch(query: String) {
        let fetcher = Fetcher(query: query) { result, error in
            if let error = error {
                //Handle it.
                print("Error \(error)")
            }
            else if let result = result {
                self.results = result.map { oneResult in return oneResult.text }
            }
        }
        switcher.switchTo(fetcher)
    }

    @IBAction func refresh(sender: AnyObject) {
        throttle.cancel()
        runFetch(currentText)
    }
}