Add a border to a UIButton. Original code - http://stackoverflow.com/a/21881788/1077789

UIButton+Border.swift

import Foundation
import UIKit

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)
    }
}

@elsurudo UIButtonBorderSide enum causes the problem - it's not bridgable to ObjC, so any methods which use it are also not bridgable. Only enums which have Int/UInt/etc as raw value can be bridged to ObjC.

Here, I modified this so you can add borders to multiple sides (or a single one) in one call. I don't know if it's possible to send pull requests or not for gists, so I'm just adding this as a comment.

https://gist.github.com/BrettRToomey/728c6f68ffbae47aa0b1638229e7367e

Here is the code for the Obj-C fellows

- (void)addBorderForSide:(UIButtonBorderSide)side color:(UIColor *)color width:(CGFloat)width{

    CALayer *border = [CALayer layer];

    border.backgroundColor = [color CGColor];

    switch (side) {
        case Top:
            border.frame = CGRectMake(0, 0, self.frame.size.width, width);
            break;
        case Bottom:
            border.frame = CGRectMake(0, self.frame.size.height - width, self.frame.size.width, width);
            break;
        case Left:
            border.frame = CGRectMake(0, 0, width, self.frame.size.height);
            break;
        case Right:
            border.frame = CGRectMake(self.frame.size.width - width, 0, width, self.frame.size.height);
            break;
        default:
            break;
    }

    [self.layer addSublayer:border];

}

see my answer here: www.stackoverflow.com/a/40222533/2594699

Swift 4 + we can add this extension to UIView so its available across more elements.

public enum UIButtonBorderSide {
    case top, bottom, left, right
}

extension UIView {
    
    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)
    }
}

lmL