在Swift中的UITextView上放置阴影

let textView = UITextView(frame: CGRect(x: 0, y: 0, width: 200, height: 100))

textView.text = "Hello, World!"
textView.font = UIFont.systemFont(ofSize: 16)
textView.textColor = UIColor.black

let shadowLayer = CALayer()
shadowLayer.shadowColor = UIColor.black.cgColor
shadowLayer.shadowOpacity = 0.5
shadowLayer.shadowOffset = CGSize(width: 2, height: 2)
shadowLayer.shadowRadius = 4

textView.layer.addSublayer(shadowLayer)
shadowLayer.frame = textView.bounds

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let textView = UITextView(frame: CGRect(x: 0, y: 0, width: 200, height: 100))
        textView.text = "Hello, World!"
        textView.font = UIFont.systemFont(ofSize: 16)
        textView.textColor = UIColor.black
        
        let shadowLayer = CALayer()
        shadowLayer.shadowColor = UIColor.black.cgColor
        shadowLayer.shadowOpacity = 0.5
        shadowLayer.shadowOffset = CGSize(width: 2, height: 2)
        shadowLayer.shadowRadius = 4
        
        textView.layer.addSublayer(shadowLayer)
        shadowLayer.frame = textView.bounds
        
        view.addSubview(textView)
    }
}