Setup global appearance of custom font in your whole app.
func setupGlobalAppearance(){
//global Appearance settings
let customFont = UIFont.appRegularFontWith(size: 17)
UIBarButtonItem.appearance().setTitleTextAttributes([NSAttributedStringKey.font: customFont], for: .normal)
UITextField.appearance().substituteFontName = Constants.App.regularFont
UILabel.appearance().substituteFontName = Constants.App.regularFont
UILabel.appearance().substituteFontNameBold = Constants.App.boldFont
}