iOS UIFont Sensible Defaults

UIFont+Extensions.swift

import Foundation

extension UIFont {
    class func systemFontOfSize(size: CGFloat) -> UIFont {
        return UIFont(name: "HelveticaNeue", size: size)!
    }
    
    class func italicSystemFontOfSize(size: CGFloat) -> UIFont {
        return UIFont(name: "HelveticaNeue-Italic", size: size)!
    }
    
    class func boldSystemFontOfSize(size: CGFloat) -> UIFont {
        return UIFont(name: "HelveticaNeue-Bold", size: size)!
    }
    
    class func mediumSystemFontOfSize(size: CGFloat) -> UIFont {
        return UIFont(name: "HelveticaNeue-Medium", size: size)!
    }
    
    class func lightSystemFontOfSize(size: CGFloat) -> UIFont {
        return UIFont(name: "HelveticaNeue-Light", size: size)!
    }
    
    class func thinSystemFontOfSize(size: CGFloat) -> UIFont {
        return UIFont(name: "HelveticaNeue-Thin", size: size)!
    }
    
    class func ultraLightSystemFontOfSize(size: CGFloat) -> UIFont {
        return UIFont(name: "HelveticaNeue-UltraLight", size: size)!
    }
    
    class func preferredFontForTextStyle(style: NSString) -> UIFont {
        switch style {
            case UIFontTextStyleBody:
                return UIFont.systemFontOfSize(15)
            case UIFontTextStyleHeadline:
                return UIFont.lightSystemFontOfSize(30)
            case UIFontTextStyleSubheadline:
                return UIFont.lightSystemFontOfSize(17)
            case UIFontTextStyleFootnote:
                return UIFont.systemFontOfSize(13)
            case UIFontTextStyleCaption1:
                return UIFont.systemFontOfSize(12)
            case UIFontTextStyleCaption2:
                return UIFont.systemFontOfSize(11)
            default:
                return UIFont.systemFontOfSize(15)
        }
    }
}

This code should be very useful, but i get a lot of errors. I'm using XCode 7.

Still in Xcode 7.0 (7A220)...
Did you manage to solve the problem?

maybe add "@nonobjc" above each class func