从iOS照片库中选择的图片不显示在UIImageView中

Question

我试图用UIImagePickerController显示从照片库中选取的图像，但是当我选择图像时，没有任何反应。

我所做的只是从Apple's Swift tutorial开始，所以我猜这个代码不应该是错的。它在模拟器和真实设备中都不起作用。我尝试了使用Google搜索时发现的所有建议。我的代码：

import UIKit 

class ViewController: UIViewController, UITextFieldDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate { 

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

override func viewDidLoad() { 
    super.viewDidLoad() 
    nameTextField.delegate = self 
} 

//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() 

    // Only allow photos to be picked, not taken. 
    imagePickerController.sourceType = .photoLibrary 

    // Make sure ViewController is notified when the user picks an image. 
    imagePickerController.delegate = self 
    present(imagePickerController, animated: true, completion: nil) 

    func imagePickerControllerDidCancel(picker: UIImagePickerController) { 
     // Dismiss the picker if the user canceled. 
     dismiss(animated: true, completion: nil) 
    } 

    func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) { 

     // The info dictionary may contain multiple representations of the image. You want to use the original. 
     guard let selectedImage = info[UIImagePickerControllerOriginalImage] as? UIImage else { 
      fatalError("Expected a dictionary containing an image, but was provided the following: \(info)") 
     } 

     // Set photoImageView to display the selected image. 
     photoImageView.image = selectedImage 

     // Dismiss the picker. 
     dismiss(animated: true, completion: nil) 
    } 
} 

@IBAction func setDefaultLabelText(sender: UIButton) { 
    mealNameLabel.text = "Default Text" 
} 

//MARK: UITextFieldDelegate 

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

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

如有必要，我可以提供更多信息。提前致谢。

Answer 1

您的委托方法在按钮操作范围内。

您必须在selectImageFromPhotoLibrary作用域中编写UIImagePickerControllerDelegate方法，并写入正确的签名。

就像这样：

@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() 

    // Only allow photos to be picked, not taken. 
    imagePickerController.sourceType = .photoLibrary 

    // Make sure ViewController is notified when the user picks an image. 
    imagePickerController.delegate = self 
    present(imagePickerController, animated: true, completion: nil) 


    } 
func imagePickerControllerDidCancel(_ picker: UIImagePickerController) { 
      // Dismiss the picker if the user canceled. 
      dismiss(animated: true, completion: nil) 
     } 

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) { 

     // The info dictionary may contain multiple representations of the image. You want to use the original. 
     guard let selectedImage = info[UIImagePickerControllerOriginalImage] as? UIImage else { 
      fatalError("Expected a dictionary containing an image, but was provided the following: \(info)") 
     } 

     // Set photoImageView to display the selected image. 
     photoImageView.image = selectedImage 

     // Dismiss the picker. 
     dismiss(animated: true, completion: nil) 
    }