它是UIButton圆角边框的全局方法

class func setRoundedBorderButton(btn:UIButton)
{
   btn.layer.cornerRadius = btn.frame.size.height/2
   btn.layer.borderWidth = 0.5
   btn.layer.borderColor = UIColor.darkGray.cgColor
}

你可以使用UIButton的子类来根据你的需要定制UIButton。

访问这个github回购参考

class RoundedRectButton: UIButton {

    var selectedState: Bool = false

    override func awakeFromNib() {
        super.awakeFromNib()
        layer.borderWidth = 2 / UIScreen.main.nativeScale
        layer.borderColor = UIColor.white.cgColor
        contentEdgeInsets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
    }


    override func layoutSubviews(){
        super.layoutSubviews()
        layer.cornerRadius = frame.height / 2
        backgroundColor = selectedState ? UIColor.white : UIColor.clear
        self.titleLabel?.textColor = selectedState ? UIColor.green : UIColor.white
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        selectedState = !selectedState
        self.layoutSubviews()
    }
}

使用button.layer。cornerRadius, button.layer.borderColor和button.layer.borderWidth。 注意borderColor需要CGColor，所以你可以说(Swift 3/4):

button.backgroundColor = .clear
button.layer.cornerRadius = 5
button.layer.borderWidth = 1
button.layer.borderColor = UIColor.black.cgColor

要在故事板中完成这项工作(接口构建器检查器)

在IBDesignable的帮助下，我们可以为UIButton添加更多的界面构建器检查器选项，并在故事板上调整它们。首先，将以下代码添加到项目中。

@IBDesignable extension UIButton {

    @IBInspectable var borderWidth: CGFloat {
        set {
            layer.borderWidth = newValue
        }
        get {
            return layer.borderWidth
        }
    }

    @IBInspectable var cornerRadius: CGFloat {
        set {
            layer.cornerRadius = newValue
        }
        get {
            return layer.cornerRadius
        }
    }

    @IBInspectable var borderColor: UIColor? {
        set {
            guard let uiColor = newValue else { return }
            layer.borderColor = uiColor.cgColor
        }
        get {
            guard let color = layer.borderColor else { return nil }
            return UIColor(cgColor: color)
        }
    }
}

然后简单地设置storyboard上按钮的属性。

import UIKit

@IBDesignable
class RoundedButton: UIButton {
    
    @IBInspectable var cornerRadius: CGFloat = 8
    @IBInspectable var borderColor: UIColor? = .lightGray
    
    override func draw(_ rect: CGRect) {
        layer.cornerRadius = cornerRadius
        layer.masksToBounds = true
        layer.borderWidth = 1
        layer.borderColor = borderColor?.cgColor
        
    }
    
    
}

我认为最简单和最干净的方法是使用协议来避免继承和代码重复。 您可以直接从故事板更改此属性

protocol Traceable {
    var cornerRadius: CGFloat { get set }
    var borderColor: UIColor? { get set }
    var borderWidth: CGFloat { get set }
}

extension UIView: Traceable {

    @IBInspectable var cornerRadius: CGFloat {
        get { return layer.cornerRadius }
        set {
            layer.masksToBounds = true
            layer.cornerRadius = newValue
        }
    }

    @IBInspectable var borderColor: UIColor? {
        get {
            guard let cgColor = layer.borderColor else { return nil }
            return  UIColor(cgColor: cgColor)
        }
        set { layer.borderColor = newValue?.cgColor }
    }

    @IBInspectable var borderWidth: CGFloat {
        get { return layer.borderWidth }
        set { layer.borderWidth = newValue }
    }
}

更新

在这个链接中，您可以找到一个使用Traceable协议实用程序的示例