这个类是基于所有的评论和建议的答案，也可以直接从xcode设计。复制到你的项目并插入任何UIButton并更改为使用自定义类，现在只需从xcode中选择正常和/或高亮显示状态的边框或背景颜色。

//
//  RoundedButton.swift
//

import UIKit

@IBDesignable
class RoundedButton:UIButton {

    @IBInspectable var borderWidth: CGFloat = 0 {
        didSet {
            layer.borderWidth = borderWidth
        }
    }
    //Normal state bg and border
    @IBInspectable var normalBorderColor: UIColor? {
        didSet {
            layer.borderColor = normalBorderColor?.CGColor
        }
    }

    @IBInspectable var normalBackgroundColor: UIColor? {
        didSet {
            setBgColorForState(normalBackgroundColor, forState: .Normal)
        }
    }


    //Highlighted state bg and border
    @IBInspectable var highlightedBorderColor: UIColor?

    @IBInspectable var highlightedBackgroundColor: UIColor? {
        didSet {
            setBgColorForState(highlightedBackgroundColor, forState: .Highlighted)
        }
    }


    private func setBgColorForState(color: UIColor?, forState: UIControlState){
        if color != nil {
            setBackgroundImage(UIImage.imageWithColor(color!), forState: forState)

        } else {
            setBackgroundImage(nil, forState: forState)
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        layer.cornerRadius = layer.frame.height / 2
        clipsToBounds = true

        if borderWidth > 0 {
            if state == .Normal && !CGColorEqualToColor(layer.borderColor, normalBorderColor?.CGColor) {
                layer.borderColor = normalBorderColor?.CGColor
            } else if state == .Highlighted && highlightedBorderColor != nil{
                layer.borderColor = highlightedBorderColor!.CGColor
            }
        }
    }

}

//Extension Required by RoundedButton to create UIImage from UIColor
extension UIImage {
    class func imageWithColor(color: UIColor) -> UIImage {
        let rect: CGRect = CGRectMake(0, 0, 1, 1)
        UIGraphicsBeginImageContextWithOptions(CGSizeMake(1, 1), false, 1.0)
        color.setFill()
        UIRectFill(rect)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }
}

这个类是基于所有的评论和建议的答案，也可以直接从xcode设计。复制到你的项目并插入任何UIButton并更改为使用自定义类，现在只需从xcode中选择正常和/或高亮显示状态的边框或背景颜色。

//
//  RoundedButton.swift
//

import UIKit

@IBDesignable
class RoundedButton:UIButton {

    @IBInspectable var borderWidth: CGFloat = 0 {
        didSet {
            layer.borderWidth = borderWidth
        }
    }
    //Normal state bg and border
    @IBInspectable var normalBorderColor: UIColor? {
        didSet {
            layer.borderColor = normalBorderColor?.CGColor
        }
    }

    @IBInspectable var normalBackgroundColor: UIColor? {
        didSet {
            setBgColorForState(normalBackgroundColor, forState: .Normal)
        }
    }


    //Highlighted state bg and border
    @IBInspectable var highlightedBorderColor: UIColor?

    @IBInspectable var highlightedBackgroundColor: UIColor? {
        didSet {
            setBgColorForState(highlightedBackgroundColor, forState: .Highlighted)
        }
    }


    private func setBgColorForState(color: UIColor?, forState: UIControlState){
        if color != nil {
            setBackgroundImage(UIImage.imageWithColor(color!), forState: forState)

        } else {
            setBackgroundImage(nil, forState: forState)
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        layer.cornerRadius = layer.frame.height / 2
        clipsToBounds = true

        if borderWidth > 0 {
            if state == .Normal && !CGColorEqualToColor(layer.borderColor, normalBorderColor?.CGColor) {
                layer.borderColor = normalBorderColor?.CGColor
            } else if state == .Highlighted && highlightedBorderColor != nil{
                layer.borderColor = highlightedBorderColor!.CGColor
            }
        }
    }

}

//Extension Required by RoundedButton to create UIImage from UIColor
extension UIImage {
    class func imageWithColor(color: UIColor) -> UIImage {
        let rect: CGRect = CGRectMake(0, 0, 1, 1)
        UIGraphicsBeginImageContextWithOptions(CGSizeMake(1, 1), false, 1.0)
        color.setFill()
        UIRectFill(rect)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }
}

基于@returntrue答案，我设法在接口生成器中实现它。

为了得到圆角按钮，使用界面生成器添加一个Key Path = "图层。按钮的标识检查器的“用户定义运行时属性”中的“Type =“Number”，Value =“10”(或其他需要的值)的“cornerRadius”。

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
        
    }
    
    
}

我认为这是简单的形式

Button1.layer.cornerRadius = 10(Half of the length and width)
Button1.layer.borderWidth = 2

@IBOutlet weak var button: UIButton!

...

我认为对于半径来说，这个参数足够了:

button.layer.cornerRadius = 5