Setup global appearance of custom font in your whole app.

AppDelegate.swift

 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
        
  }