Extension file

Extension.swift

import Foundation
import UIKit
extension UILabel {
    var substituteFontName : String {
        get { return self.font.fontName }
        set {
            if self.font.fontName.range(of:"-Bd") == nil {
                self.font = UIFont(name: newValue, size: self.font.pointSize)
            }
        }
    }
    var substituteFontNameBold : String {
        get { return self.font.fontName }
        set {
            if self.font.fontName.range(of:"-Bd") != nil {
                self.font = UIFont(name: newValue, size: self.font.pointSize)
            }
        }
    }
}
extension UITextField {
    var substituteFontName : String {
        get { return self.font!.fontName }
        set { self.font = UIFont(name: newValue, size: (self.font?.pointSize)!) }
    }
}
extension UIFont {
    class func appRegularFontWith( size:CGFloat ) -> UIFont{
        return  UIFont(name: Constants.App.regularFont, size: size)!
    }
    class func appBoldFontWith( size:CGFloat ) -> UIFont{
        return  UIFont(name: Constants.App.boldFont, size: size)!
    }    
}