在 Swift 中的 UITextView 上放置阴影

Posted 2023-03-13

【中文标题】在 Swift 中的 UITextView 上放置阴影

【英文标题】：Drop shadow on UITextView in Swift

【发布时间】：2018-08-15 11:41:33

【问题描述】：

我搜索了一段时间，但不知道如何实施我找到的解决方案。

下面的帖子定义了我真正想要的东西，它也有一个解决方案，但在 Objective-c 中。我尝试实施该解决方案，但实施后文本开始不显示。

UITextView bottom shadow on text

class AggrementView: UIView, UITextViewDelegate 

let acceptBtn = RippleButton()
let kvkkTextView = UITextView()

private let containerView = UIView()

override init(frame: CGRect) 
    super.init(frame: frame)
    setupUI()
    setupConstraints()

public convenience init(text: String, imageName: String)
    self.init()


public convenience init(text: String, imageName: String, senderColor: UIColor)
    self.init()

required public init?(coder aDecoder: NSCoder) 
    fatalError("init(coder:) has not been implemented")


private func setupUI()
    self.backgroundColor = .clear

    acceptBtn.translatesAutoresizingMaskIntoConstraints = false
    //acceptBtn.backgroundColor = UIColor(red:0.40, green:0.69, blue:0.07, alpha:1.0)
    acceptBtn.backgroundColor = UIColor.gray
    acceptBtn.layer.cornerRadius = 6.0
    acceptBtn.setTitle("Onaylıyorum", for: UIControlState.normal)
    acceptBtn.titleLabel?.font = UIFont(name: "Corbert-Regular", size: 20)!
    acceptBtn.setTitleColor(UIColor.flatWhite, for: UIControlState.normal)
    //acceptBtn.setAllSideShadow(shadowShowSize: 8.0)
    acceptBtn.accessibilityIdentifier = "acceptBtn"
    acceptBtn.isEnabled = false
    acceptBtn.setTitleColor(UIColor.lightGray, for: .disabled)

    kvkkTextView.font = UIFont(name: "Corbert-Regular", size: 15)!
    kvkkTextView.setContentOffset(CGPoint.zero, animated: false)
    kvkkTextView.layer.cornerRadius = 6.0
    kvkkTextView.backgroundColor = .clear
    kvkkTextView.layer.borderColor = UIColor.flatGray.cgColor
    kvkkTextView.textColor = UIColor.flatWhite
    kvkkTextView.delegate = self
    kvkkTextView.isEditable = false

    containerView.backgroundColor = .clear
    containerView.layer.cornerRadius = 6.0

    self.addSubview(containerView)
    containerView.addSubview(acceptBtn)
    containerView.addSubview(kvkkTextView)


private func setupConstraints()
    containerView.anchor(self.topAnchor, left: self.leftAnchor, bottom: self.bottomAnchor, right: self.rightAnchor, topConstant: 90, leftConstant: 10, bottomConstant: 20, rightConstant: 10, widthConstant: 0, heightConstant: 0)
    kvkkTextView.anchor(self.containerView.topAnchor, left: self.containerView.leftAnchor, bottom: self.acceptBtn.topAnchor, right: self.containerView.rightAnchor, topConstant: 0, leftConstant: 0, bottomConstant: 20, rightConstant: 0, widthConstant: 0, heightConstant: 0)
    acceptBtn.anchor(nil, left: self.containerView.leftAnchor, bottom: self.containerView.bottomAnchor, right: self.containerView.rightAnchor, topConstant: 0, leftConstant: 10, bottomConstant: 10, rightConstant: 10, widthConstant: 0, heightConstant: 60)

func scrollViewDidScroll(_ scrollView: UIScrollView) 

    if (scrollView.contentOffset.y >= scrollView.contentSize.height - scrollView.frame.size.height) 
        print( "View scrolled to the bottom" )
        UIView.animate(withDuration: 0.5) 
            self.acceptBtn.backgroundColor = UIColor(red:0.40, green:0.69, blue:0.07, alpha:1.0)
            self.acceptBtn.isEnabled = true
        
    

    let color = UIColor.lightGray
    guard
        let verticalIndicator = scrollView.subviews.last as? UIImageView,
        verticalIndicator.backgroundColor != color,
        verticalIndicator.image?.renderingMode != .alwaysTemplate
        else  return 
    verticalIndicator.layer.masksToBounds = true
    verticalIndicator.layer.cornerRadius = verticalIndicator.frame.width / 2
    verticalIndicator.backgroundColor = color
    verticalIndicator.image = verticalIndicator.image?.withRenderingMode(.alwaysTemplate)
    verticalIndicator.tintColor = .clear

图片参考：@user2213271 在UITextView bottom shadow on text 帖子中

这是我试过的梯度代码：

func applyShadow()
var layerWidth: CGFloat = 8.0
var gl1 = CAGradientLayer()
var col1 = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 1.0).cgColor
var col2 = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.0).cgColor
gl1.colors = [col2, col1, col1, col2]
gl1.locations = [0.0, 0.0, 0.85, 1.0]
//underTextView - this is my UIView
gl1.frame = CGRect(x: 0, y: 0, width: underTextView.frame.width - layerWidth, height: underTextView.frame.height)
//layer for scrollIndicator - it must be visible always good
var gl2 = CAGradientLayer()
gl2.colors = [col1, col1]
gl2.locations = [0.0, 1.0]
gl2.frame = CGRect(x: underTextView.frame.width - layerWidth, y: 0, width: layerWidth, height: underTextView.frame.height)
//create main layer
var gl = CAGradientLayer()
gl.addSublayer(gl1)
gl.addSublayer(gl2)
//add to mask of UIView
underTextView.layer.mask = gl

【参考方案1】：

您似乎忘记在设置kvkkTextView 的锚点之前添加kvkkTextView.translatesAutoresizingMaskIntoConstraints = false。所以你的kvkkTextView 无法从约束中获取它的框架。

【讨论】：

是的。感谢您的提醒。我添加了但没有任何改变。我猜这与cliptobounds有关。

您将 kvkkTextView 的高度和宽度约束设置为 0。如果您没有执行“如果约束为 0，则不使用约束”之类的控制，这可能是原因。