How do you adjust text kerning using Interface Builder in Xcode 7?

Create a subclass of UILabel call it KerningLabel have it be comprised of the following code:

import UIKit

@IBDesignable
class KerningLabel: UILabel {

    @IBInspectable var kerning: CGFloat = 0.0 {
        didSet {
            if attributedText?.length == nil { return }

            let attrStr = NSMutableAttributedString(attributedString: attributedText!)
            let range = NSMakeRange(0, attributedText!.length)
            attrStr.addAttributes([NSAttributedStringKey.kern: kerning], range: range)
            attributedText = attrStr
        }
    }
}

Drag out a label. Change it to your UILabel subclass. Adjust the kerning as desired.

In obj-c:

.h

IB_DESIGNABLE
@interface KerningLabel : UILabel

@property (nonatomic) IBInspectable CGFloat kerning;

@end

.m

@implementation KerningLabel

- (void)setKerning:(CGFloat)kerning
{
    _kerning = kerning;
    if(self.attributedText)
    {
        NSMutableAttributedString *attribString = [[NSMutableAttributedString alloc]initWithAttributedString:self.attributedText];
        [attribString addAttribute:NSKernAttributeName value:@(kerning) range:NSMakeRange(0, self.attributedText.length)];
        self.attributedText = attribString;
    }
}

@end

You can actually do this without the use of a subclass through an extension.

import UIKit

@IBDesignable
extension UILabel {
    @IBInspectable
    public var kerning:CGFloat {
        set{
            if let currentAttibutedText = self.attributedText {
                let attribString = NSMutableAttributedString(attributedString: currentAttibutedText)
                attribString.addAttributes([NSKernAttributeName:newValue], range:NSMakeRange(0, currentAttibutedText.length))
                self.attributedText = attribString
            }
        } get {
            var kerning:CGFloat = 0
            if let attributedText = self.attributedText {
                attributedText.enumerateAttribute(NSKernAttributeName,
                                                  in: NSMakeRange(0, attributedText.length),
                                                  options: .init(rawValue: 0)) { (value, range, stop) in
                                                    kerning = value as? CGFloat ?? 0
                }
            }
            return kerning
        }
    }
}

While this won't actually show up in interface builder it will show up and work when you run your app.