Set a border for UIButton in Storyboard

You can use key path.

For example the corner radius (layer.cornerRadius) as describe on the image. You will not be able to see the effects on storyboard, cause this parameters are evaluated at runtime. Now you can use a swift category in UIView (code bellow the picture) in with @IBInspectable to show the result at the storyboard (If you are using the category, use only cornerRadius and not layer.cornerRadius as a key path.

---

extension UIView {
    @IBInspectable var cornerRadius: CGFloat {
        get {
            return layer.cornerRadius
        }
        set {
            layer.cornerRadius = newValue
            layer.masksToBounds = newValue > 0
        }
    }
}

---

Here is category from Peter DeWeese answer that allow use keypath layer.borderUIColor to set the border color.

CALayer+XibConfiguration.h:

#import <QuartzCore/QuartzCore.h>
#import <UIKit/UIKit.h>

@interface CALayer(XibConfiguration)

// This assigns a CGColor to borderColor.
@property(nonatomic, assign) UIColor* borderUIColor;

@end

CALayer+XibConfiguration.m:

#import "CALayer+XibConfiguration.h"

@implementation CALayer(XibConfiguration)

-(void)setBorderUIColor:(UIColor*)color
{
    self.borderColor = color.CGColor;
}

-(UIColor*)borderUIColor
{
    return [UIColor colorWithCGColor:self.borderColor];
}

@end

Swift 3 If you want to see the result in IB when you use IBInspectable, you have to extend UIView and add the properties to that class, i.e.

@IBDesignable class MyView: UIView {}

extension MyView {
    @IBInspectable var cornerRadius: CGFloat {
        get {
            return layer.cornerRadius
        }
        set {
            layer.cornerRadius = newValue
            layer.masksToBounds = newValue > 0
        }
    }

    @IBInspectable var borderWidth: CGFloat {
        get {
            return layer.borderWidth
        }
        set {
            layer.borderWidth = newValue
            layer.masksToBounds = newValue > 0
        }
    }

    @IBInspectable var borderColor: UIColor {
        get {
            return UIColor.init(cgColor: layer.borderColor!)
        }
        set {
            layer.borderColor = newValue.cgColor
        }
    }
}

reference: http://nshipster.com/ibinspectable-ibdesignable/