Ios 如何允许用户使用 Swift Select 图像

我正在用Swift编写我的第一个iOS应用程序(仅限iPhone).主应用程序视图应允许用户从照片库中 Select 图像.

我找到了以下ViewController.swift的示例代码:

class ViewController: UIImagePickerController, UINavigationControllerDelegate, UIImagePickerControllerDelegate  {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

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

    func tableView(tableView: UITableView!, didSelectRowAtIndexPath indexPath: NSIndexPath!) {

        var imagePickerController = UIImagePickerController()
        imagePickerController.delegate = self
        imagePickerController.sourceType = UIImagePickerControllerSourceType.SavedPhotosAlbum
        imagePickerController.allowsEditing = true
        self.presentViewController(imagePickerController, animated: true, completion: { imageP in

        })
    }


    func imagePickerController(picker: UIImagePickerController!, didFinishPickingImage image: UIImage!, editingInfo: NSDictionary!) {
        let selectedImage : UIImage = image
        println(selectedImage)
    }

}

并具有以下视图控制器场景-

View Controller
 - Top Layout Guide
 - Bottom Layout Guide
 - View
   - Image View
First Responder
Exit

但当我启动应用程序时，只显示黑屏.我做错了什么？ 我在Objective-C找到了另外sample code个，这对我没什么帮助.