最近新学ios开发，按照下面教程中的步骤一步步敲代码，但是在获取图片这块就是触发不了选取图片，反复重来好几遍了，代码又只能看懂大概，我能想到的就是tap gesture没有触发到，不知道为什么，麻烦各位高手给点提示。 https://developer.apple.com/library/ios/referencelibrary/GettingStarted/DevelopiOSAppsSwift/Lesson4.html#//apple_ref/doc/uid/TP40015214-CH6-SW1

//
//  ViewController.swift
//  FoodTracker02
//

import UIKit

class ViewController: UIViewController, UITextFieldDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

    // Mark: Properties
    @IBOutlet weak var mealNameLabel: UILabel!
    @IBOutlet weak var nameTextField: UITextField!
    @IBOutlet weak var photoImageView: UIImageView!

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

    // Mark: UITextFieldDelegate
    func textFieldShouldReturn(textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }

    func textFieldDidEndEditing(textField: UITextField) {
        mealNameLabel.text = textField.text
    }

    // Mark: UIImagePickerControllerDelegate
    func imagePickerControllerDidCancel(picker: UIImagePickerController) {
        // Dismiss the picker if user canceld.
        dismissViewControllerAnimated(true, completion: nil)
    }

    func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]){
        let selectedImage = info[UIImagePickerControllerOriginalImage] as! UIImage
        // Set photoImageView to display the selected image
        photoImageView.image = selectedImage
        dismissViewControllerAnimated(true, completion: nil)
    }

    // Mark: Actions
    @IBAction func selectImageFromPhotoLibrary(sender: UITapGestureRecognizer) {
        // Hide the keyboard.
        nameTextField.resignFirstResponder()

        // UIImagePickerController is a view controller that lets a user pick media from their photo library.
        let imagePickerController = UIImagePickerController()
        imagePickerController.sourceType = .PhotoLibrary

        // Make sure ViewController is notified when the user picks an image.
        imagePickerController.delegate = self

        presentViewController(imagePickerController, animated: true, completion: nil)
    }

    @IBAction func setDefaultLabel(sender: UIButton) {
        mealNameLabel.text = "Defualt Label"
    }

}