Question

我试图了解有关委托模式的更多信息。我编写了一个访问用户相机胶卷的应用程序，我希望在用户选择图像后在视图控制器上显示该图像。以下是我到目前为止的情况：

import UIKit

class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

    @IBOutlet weak var imagePickerView: UIImageView!

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

    // Delegate Methods
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        if let image = info[UIImagePickerControllerOriginalImage] as? UIImage {
            imagePickerView.image = image
        }
    }

    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        self.dismiss(animated: true, completion: nil)
    }

    @IBAction func pickAnImage(_ sender: Any) {

        let pickerController = UIImagePickerController()
        present(pickerController, animated: true, completion: nil)
    }
}

相机胶卷按预期显示，取消按钮关闭模式。选择图像也会取消模式，但该图像不会显示在屏幕上。我已确认我的imagePickerController已被更正为引用。我错过了什么？

Answer 1

选择图像后，您必须关闭控制器，可能以下详细功能可以帮助您。

对于Swift 4.2：

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

    var selectedImageFromPicker: UIImage?
    if let editedImage = info[.editedImage] as? UIImage {
        selectedImageFromPicker = editedImage
    } else if let originalImage = info[.originalImage] as? UIImage {
        selectedImageFromPicker = originalImage
    }

    if let selectedImage = selectedImageFromPicker {
        imageView.image = selectedImage
    }
    dismiss(animated: true, completion: nil)
}

在Swift 4.2之前：

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

    var selectedImageFromPicker: UIImage?
    if let editedImage = info[UIImagePickerControllerEditedImage] as? UIImage {
        selectedImageFromPicker = editedImage
    } else if let originalImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
        selectedImageFromPicker = originalImage
    }

    if let selectedImage = selectedImageFromPicker {
        imageView.image = selectedImage
    }
    dismiss(animated: true, completion: nil)
}

由于我从这个答案中收到了很多分数，因此我添加了一个更简洁的答案（将图像设置为imageView只需要一行）。

奖金回答：

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    imageView.image = (info[.editedImage] ?? info[.originalImage]) as? UIImage
    dismiss(animated: true)
}

Answer 2

您需要将视图控制器设置为pickerController的委托

// pickerController.delegate = self

同时检查imagePickerView插座是否已连接。

Answer 3

确保您已在info.plist文件中包含所有内容
确保您设置了所有代理
确保用于显示图像的内容（例如，如果编辑设置为true，则UIImagePickerControllerEditedImage其他UIImagePickerControllerOriginalImage）

在Swift中使用UIIamgePickerControllerDelegate在屏幕上显示所选图像

3 个答案: