Does not conform to protocol UIPickerViewDataSource
<p>I don't know what's wrong with my code. I tried to follow the tutorial but same error happen.</p>

<p>Error: </p>

<blockquote>
  <p>Type 'FourthViewController' does not conform to protocol 'UIPickerViewDataSource'</p>
</blockquote>

<p>Here is my code: </p>

<pre class="lang-java prettyprint-override"><code>import UIKit

let characters = ["Jaja Bink", "Luke", "Han Solo", "Princess Leia"];

let weapons = ["LightSaber", "Pistol", "Keris"];

class FourthViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

    @IBOutlet weak var doublePicker: UIPickerView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func numberOfComponentsInPickerView(pickerView: UIPickerView) -&gt; Int {
        return 2
    }


    func pickerView(pickerView: UIPickerView,
                    titleForRow row: Int,
                                forComponent component: Int) -&gt; String? {

        if component == 0 {
            return characters[row]
        } else {
            return weapons[row]
        }

    }

    func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -&gt; Int? {
        if component == 0 {
            return characters.count
        } else {
            return weapons.count
        }
    }

}
</code></pre>