UIView shadow and InterfaceBuilder

Add a file named UIView.swift in your project (or just paste this in any file) :

import UIKit

@IBDesignable extension UIView {

    /* The color of the shadow. Defaults to opaque black. Colors created
    * from patterns are currently NOT supported. Animatable. */
    @IBInspectable var shadowColor: UIColor? {
        set {
            layer.shadowColor = newValue!.CGColor
        }
        get {
            if let color = layer.shadowColor {
                return UIColor(CGColor:color)
            }
            else {
                return nil
            }
        }
    }

    /* The opacity of the shadow. Defaults to 0. Specifying a value outside the
    * [0,1] range will give undefined results. Animatable. */
    @IBInspectable var shadowOpacity: Float {
        set {
            layer.shadowOpacity = newValue
        }
        get {
            return layer.shadowOpacity
        }
    }

    /* The shadow offset. Defaults to (0, -3). Animatable. */
    @IBInspectable var shadowOffset: CGPoint {
        set {
            layer.shadowOffset = CGSize(width: newValue.x, height: newValue.y)
        }
        get {
            return CGPoint(x: layer.shadowOffset.width, y:layer.shadowOffset.height)
        }
    }

    /* The blur radius used to create the shadow. Defaults to 3. Animatable. */
    @IBInspectable var shadowRadius: CGFloat {
        set {
            layer.shadowRadius = newValue
        }
        get {
            return layer.shadowRadius
        }
    }
}

Then this will be available in Interface Builder for every view in the Utilities Panel > Attributes Inspector :

You can easily set the shadow now.

Notes:
- The shadow will only appear at runtime.
- clipsToBounds should be false (by default it is)

I know this question has long, but recently i was in a similar situation so i decided to put my answer for those who are in a situation like this.

I wanted to be able to set the borderColor and shadowColor on an UIView through the Interface Builder, but the type of a layer’s borderColor property is CGColor (just like shadowColor) which is not one of the types allowed to be changed in the user-defined runtime attributes feature.

So i made an extension for CALayerand i added two properties called borderColorIB and shadowColorIB that are of type UIColor:

RuntimeAttributes.h

@import QuartzCore;

@interface CALayer (IBConfiguration)

@property(nonatomic, assign) UIColor* borderColorIB;
@property(nonatomic, assign) UIColor* shadowColorIB;

@end

RuntimeAttributes.m

#import <UIKit/UIKit.h>
#import "RuntimeAttributes.h"

@implementation CALayer (IBConfiguration)

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

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

-(void)setShadowColorIB:(UIColor*)color
{
    self.shadowColor = color.CGColor;
}

-(UIColor*)shadowColorIB
{
    return [UIColor colorWithCGColor:self.shadowColor];
}

@end

Now i alredy be able to set this two properties through Interface Builder like this:

1. In the 'user-defined runtime attributes' section (Identity inspector)

2. Make sure the UIView is selected, and add the following runtime attributes:

   • layer.borderWidth, Number, 1
   • layer.borderColorIB, Color, someColor <- my custom property to set the borderColor
   • layer.shadowColorIB, Color, someColor <- my custom property to set the shadowColor
   • layer.shadowOpacity, Number, 0.8
   • layer.shadowOffset, size, {5,5}
   • layer.cornerRadius, Number, 5

Here is an image to show you how i did:

... and The result will be apparent during runtime, not in Xcode:

i hope this can help some people out there!