Custom Font Sizing in Xcode 6 Size Classes not working properly with Custom Fonts

Question

Xcode 6 has a new feature where fonts and font sizes in UILabel, UITextField, and UIButton can be s

Answer 1

After trying everything, I eventually settled on a combination of the above solutions. Using Xcode 7.2, Swift 2.

import UIKit

class LabelDeviceClass : UILabel {

    @IBInspectable var iPhoneSize:CGFloat = 0 {
        didSet {
            if isPhone() {
                overrideFontSize(iPhoneSize)
            }
        }
    }

    @IBInspectable var iPadSize:CGFloat = 0 {
        didSet {
            if isPad() {
                overrideFontSize(iPadSize)
            }
        }
    }

    func isPhone() -> Bool {
        // return UIDevice.currentDevice().userInterfaceIdiom == .Phone
        return !isPad()
    }

    func isPad() -> Bool {
        // return UIDevice.currentDevice().userInterfaceIdiom == .Pad
        switch (UIScreen.mainScreen().traitCollection.horizontalSizeClass, UIScreen.mainScreen().traitCollection.verticalSizeClass) {
        case (.Regular, .Regular):
            return true
        default:
            return false
        }
    }

    func overrideFontSize(fontSize:CGFloat){
        let currentFontName = self.font.fontName
        if let calculatedFont = UIFont(name: currentFontName, size: fontSize) {
            self.font = calculatedFont
        }
    }

}

• @IBInspectable lets you set the font size in the Storyboard
• It uses a didSet observer, to avoid the pitfalls from layoutSubviews() (infinite loop for dynamic table view row heights) and awakeFromNib() (see @cocoaNoob's comment)
• It uses size classes rather than the device idiom, in hopes of eventually using this with @IBDesignable
• Sadly, @IBDesignable doesn't work with traitCollection according to this other stack article
• The trait collection switch statement is performed on UIScreen.mainScreen() rather than self per this stack article