ios – Swift NSAttributedStringKey没有正确应用前景色[复制]

参见英文答案 > How can I both stroke and fill with NSAttributedString w/ UILabel4个
我正在尝试创建一个meme生成器应用程序,以更好地理解Swift,Xdode,代理和UIKit.我试图使用NSAttributedStringKey将meme文本的颜色设置为白色并使用黑色笔划.黑色笔划正在工作,但当用户从相机胶卷中选择图像时,不会应用前景色.我已经搜索了StackOverflow,但所有的解决方案都适用于Swift 3,而不是Swift 4.我哪里出错？

我在下面列出了我的源代码.

import UIKit

class ViewController: UIViewController,UIImagePickerControllerDelegate,UINavigationControllerDelegate {

    @IBOutlet weak var imagePickerView: UIImageView!
    @IBOutlet weak var cameraButton: UIBarButtonItem!
    @IBOutlet weak var topText: UITextField!
    @IBOutlet weak var bottomText: UITextField!

    let memeTextAttributes:[String:Any] = [
        NSAttributedStringKey.strokeColor.rawValue: UIColor.black,NSAttributedStringKey.foregroundColor.rawValue: UIColor.white,NSAttributedStringKey.font.rawValue: UIFont(name: "HelveticaNeue-CondensedBlack",size: 40)!,NSAttributedStringKey.strokeWidth.rawValue: 3.0]

    override func viewDidLoad() {
        super.viewDidLoad()
        // Diable camer a button if camera ource isn't available
        cameraButton.isEnabled = UIImagePickerController.isSourceTypeAvailable(.camera)
        topText.defaultTextAttributes = memeTextAttributes
        bottomText.defaultTextAttributes = memeTextAttributes
    }

    // MARK: Delegate Methods

    func imagePickerController(_ picker: UIImagePickerController,didFinishPickingMediawithInfo info: [String : Any]) {
        if let image = info[UIImagePickerControllerOriginalImage] as? UIImage {
            imagePickerView.image = image
            self.dismiss(animated: true,completion: nil)
        }
    }

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

    @IBAction func pickAnImageFromAlbum(_ sender: Any) {
        let pickerController = UIImagePickerController()
        pickerController.delegate = self
        pickerController.sourceType = .photoLibrary
        present(pickerController,animated: true,completion: nil)
    }

    @IBAction func pickAnImageFromCamera(_ sender: Any) {
        let imagePicker = UIImagePickerController()
        imagePicker.delegate = self
        imagePicker.sourceType = .camera
        present(imagePicker,completion: nil)
    }
}

let attributes = [
        NSAttributedStringKey.strokeColor.rawValue: UIColor.black,NSAttributedStringKey.backgroundColor.rawValue: UIColor.red,NSAttributedStringKey.strokeWidth.rawValue: -4.5]