Showing UIAppearance Proxies on on values that aren't normally exposed

ForceAppearance.swift

private extension AppStyle {

    func setupAppearance() {
        setupNavBarAppearance()
        setupTableViewCellAppearance()
        setupTableAppearance()
    }

    func setupNavBarAppearance() {

        let navBarAppearance = UINavigationBar.appearanceWhenContainedInInstancesOfClasses([NavigationController.self])

        navBarAppearance.translucent = false
        navBarAppearance.shadowImage = UIImage.solidImage(color: colors.tintColor)

        let barImage = UIImage.solidImage(color: colors.navigationBackgroundColor)
        navBarAppearance.setBackgroundImage(barImage, forBarMetrics: .Default)
        let textStyle: [String:AnyObject] = [
            NSForegroundColorAttributeName: colors.navbarTextColor
        ]
        navBarAppearance.titleTextAttributes = textStyle
    }

    func setupTableViewCellAppearance() {
        let cellAppearance = UITableViewCell.appearanceWhenContainedInInstancesOfClasses([NavigationController.self])
        cellAppearance.backgroundColor = colors.backgroundColor
        let selectedView =  UIView()
        selectedView.backgroundColor = colors.selectedBackgroundColor
        cellAppearance.selectedBackgroundView = selectedView
        cellAppearance.forceInsets(UIEdgeInsets())

        let nestedClasses: [AnyObject.Type] = [UITableViewCell.self, NavigationController.self]
        let cellLabelAppearance = UILabel.appearanceWhenContainedInInstancesOfClasses(nestedClasses)
        cellLabelAppearance.forceFont(UIFont.preferredFontForTextStyle(UIFontTextStyleBody))
        cellLabelAppearance.highlightedTextColor = colors.selectedTextColor
        cellLabelAppearance.forceTextColor(colors.textColor)
    }

    func setupTableAppearance() {
        let tableViewAppearance = UITableView.appearanceWhenContainedInInstancesOfClasses([NavigationController.self])
        tableViewAppearance.backgroundColor = colors.backgroundColor
        tableViewAppearance.tableFooterView = UIView()
        tableViewAppearance.separatorColor = colors.textColor
        tableViewAppearance.forceInsets(UIEdgeInsets())
    }
}

//MARK: - Functions to force configuration of properties not exposed to UIApperarance by default

private extension UILabel {
    @objc func forceTextColor(color: UIColor) {
        textColor = color
    }

    @objc func forceFont(font: UIFont) {
        self.font = font
    }
}

private extension UITableView {
    @objc func forceInsets(edgeInsets: UIEdgeInsets) {
        separatorInset = edgeInsets
        layoutMargins = edgeInsets
    }
}

private extension UITableViewCell {
    @objc func forceInsets(edgeInsets: UIEdgeInsets) {
        separatorInset = edgeInsets
        layoutMargins = edgeInsets
    }
}