Swift: 如何从 ViewDidLoad 获取 UITextView 上的阴影？

Question

我无法在 UIImageView 内的 UITextView 上获得阴影。

我尝试了很多可能的方法。限制是，我不能覆盖 layoutMethods 因为它们出于某种原因无法访问。因此，为了演示，我将相同的代码放在 viewDidLoad 中进行调试，但无法弄清楚。请在这里解释我做错了什么。

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .black
        let imageView = UIImageView()
        imageView.image = #imageLiteral(resourceName: "guitar")
        imageView.layer.cornerRadius = 15
        imageView.clipsToBounds = true

        view.addSubview(imageView)
        imageView.translatesAutoresizingMaskIntoConstraints = false
        imageView.heightAnchor.constraint(equalToConstant: 240).isActive = true
        imageView.widthAnchor.constraint(equalToConstant: 240).isActive = true
        imageView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
        imageView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true

        let textView = UITextView(frame: CGRect.zero)
        textView.text = "This is a Sample text. This is a Sample text. This is a Sample text. This is a Sample text. This is a Sample text. "
        textView.isEditable = false
        textView.textAlignment = .left
        textView.isSelectable = false
        textView.backgroundColor = .systemBlue
        textView.textColor = UIColor.white
        textView.sizeToFit()
        textView.isScrollEnabled = false
        textView.textContainerInset = UIEdgeInsets(top: 6, left: 7, bottom: 6, right: 7)
        textView.clipsToBounds = false
        textView.layer.shadowColor = UIColor.gray.cgColor
        textView.layer.shadowRadius = 10
        textView.layer.opacity = 1
        textView.layer.shadowOffset = .zero
        textView.layer.shadowPath = UIBezierPath(rect: textView.bounds).cgPath
        textView.layer.masksToBounds = false

        imageView.addSubview(textView)
        textView.translatesAutoresizingMaskIntoConstraints = false
        textView.leftAnchor.constraint(equalTo: imageView.leftAnchor).isActive = true
        textView.bottomAnchor.constraint(equalTo: imageView.bottomAnchor).isActive = true
        textView.rightAnchor.constraint(equalTo: imageView.rightAnchor).isActive = true
    }

Answer 1

您将 LAYER 不透明度设置为 1:

textView.layer.opacity = 1

但是你需要设置图层的shadowOpacity:

//textView.layer.opacity = 1

textView.layer.shadowOpacity = 1

这应该可以解决问题。

顺便说一句，无论是否使用 .shadowPath，您都会得到相同的结果（因为 "default" 阴影路径是视图的边界/矩形）。

Swift: 如何从 ViewDidLoad 获取 UITextView 上的阴影？

Swift: How to get shadow working on UITextView from ViewDidLoad?

uitextview

ios

swift