如何更改 UIBarButtonItems 的默認字體？

Question

我想更改所有 UIBarButtonItems 的默認字體。 我在我的應用程序的根視圖 controller 中有以下代碼：

    let attributes: [NSAttributedString.Key: Any] = [.font: UIFont.systemFont(ofSize: 30)]
    UIBarButtonItem.appearance().setTitleTextAttributes(attributes, for: .normal)
    UINavigationBar.appearance().titleTextAttributes = attributes
    UINavigationBarAppearance().buttonAppearance.normal.titleTextAttributes = attributes
    UIBarButtonItemAppearance().normal.titleTextAttributes = attributes
    self.navigationItem.rightBarButtonItem = UIBarButtonItem(title: "foo", style: .plain, target: nil, action: nil)

盡管外觀發生了變化，但該條形按鈕項的字體仍然是默認字體。 如何設置默認字體？ 我知道我可以為每個單獨的條形按鈕項目設置字體，但我正在尋找一種方法來廣泛地改變它。

Answer 1

iOS 13 前

class AppDelegate : NSObject, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {

        if #available(iOS 13, *) {

        }else{
            let attributes: [NSAttributedString.Key: Any] = [.font: UIFont.systemFont(ofSize: 30)]
            UIBarButtonItem.appearance().setTitleTextAttributes(attributes, for: .normal)
            UINavigationBar.appearance().titleTextAttributes = attributes
        }

        return true
    }
}

iOS 13

class MyNavigationController : UINavigationController {

    override init(rootViewController: UIViewController) {
        super.init(rootViewController: rootViewController)
        if #available(iOS 13, *) {
            let attributes: [NSAttributedString.Key: Any] = [.font: UIFont.systemFont(ofSize: 30)]
            let appearance = UINavigationBarAppearance()
            appearance.buttonAppearance.normal.titleTextAttributes = attributes
            appearance.titleTextAttributes = attributes
            self.navigationBar.standardAppearance = appearance
        }
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

Answer 2

您可以使用 UINavigationBarAppearance 自定義所有導航欄，但您需要在導航欄的外觀代理上設置 standardAppearance - 調用如下：

UINavigationBarAppearance().buttonAppearance.normal.titleTextAttributes = attributes
UIBarButtonItemAppearance().normal.titleTextAttributes = attributes

孤立地什么也不做，因為他們創造了一個新的外觀，設置一個值，然后把它扔掉。 而是這樣做：

let appearance = UINavigationBarAppearance()
appearance.buttonAppearance.normal.titleTextAttributes = attributes
UINavigationBar.appearance().standardAppearance = appearance