围绕textview或标签快速绘制边框

Question

myLabel.layer.borderWidth = 0.5 
myLabel.layer.borderColor = UIColor.green.cgColor 

这就是绘制边框的简单答案。然而，问题是我需要仅将边界绘制到右侧和底部。我还需要另一个标签来在右上角绘制边框。我怎样才能把边界画到特定的边，而不是全部四边？

Answer 1

添加形状图层，绘制该层中的线。请注意，图层不参与自动布局，因此您需要将代码放入viewDidLayoutSubviews或子类uilabel中，然后在布局子视图中执行此操作。下面是使用的UILabel子类的游乐场例如：

import PlaygroundSupport 
    import UIKit 
    class L: UILabel { 
     var strokeColor = UIColor.blue 
     var strokeWidth = CGFloat(0.5) 
     private lazy var labelBorderLayer:CAShapeLayer = { 
      let shapeLayer = CAShapeLayer() 
      self.layer.addSublayer(shapeLayer) 
      return shapeLayer 
     }() 
     override func layoutSubviews() { 
      super.layoutSubviews() 
      let path = CGMutablePath() 
      path.move(to: CGPoint(x: 0, y: bounds.size.height)) 
      path.addLine(to: CGPoint(x: bounds.size.width, y: bounds.size.height)) 
      path.addLine(to: CGPoint(x: bounds.size.width, y: 0)) 
      labelBorderLayer.path = path 
      labelBorderLayer.strokeColor = strokeColor.cgColor 
      labelBorderLayer.lineWidth = strokeWidth 
      labelBorderLayer.fillColor = UIColor.clear.cgColor 
     } 
    } 

    let v = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200)) 
    let l = L(frame: v.frame.insetBy(dx: 50, dy: 80)) 
    v.addSubview(l) 
    l.textColor = .white 
    l.textAlignment = .center 
    l.text = "gjgkjgjgjgj" 
    v.backgroundColor = .red 
    PlaygroundPage.current.liveView = v 

Answer 2

我不知道你是否可以用实际的标签边框做到这一点。但是，你可以做类似于这个

public enum UIButtonBorderSide { 
     case Top, Bottom, Left, Right 
    } 

extension UIButton { 
public func addBorder(side: UIButtonBorderSide, color: UIColor, width: CGFloat) { 
    let border = CALayer() 
    border.backgroundColor = color.CGColor 

    switch side { 
    case .Top: 
     border.frame = CGRect(x: 0, y: 0, width: frame.size.width, height: width) 
    case .Bottom: 
     border.frame = CGRect(x: 0, y: self.frame.size.height - width, width: self.frame.size.width, height: width) 
    case .Left: 
     border.frame = CGRect(x: 0, y: 0, width: width, height: self.frame.size.height) 
    case .Right: 
     border.frame = CGRect(x: self.frame.size.width - width, y: 0, width: width, height: self.frame.size.height) 
    } 

    self.layer.addSublayer(border) 
} 
} 

这就是UIButton，但你可以很容易地适应它。

来源：https://gist.github.com/Isuru-Nanayakkara/496d5713e61125bddcf5

希望这有助于