在swift 4下更改导航控制器后退按钮上的字体

Question

Swift 4，iOS 11.2.5 Xcode 9.2

尝试更改后退按钮的字体。试过以前的解决方案，但似乎没有一个在Swift 4，iOS 11.2.5下使用我的配置，标签栏控制器内的导航控制器。

得到这个代码，第一行和最后一行都有效，但中心三行没有。

self.navigationController?.navigationBar.titleTextAttributes = [ NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!]
navigationItem.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .normal)
navigationItem.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .highlighted)
navigationItem.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .focused)
navigationItem.title = "Filter \(titleSelection!) [shake to clear]"

这是viewDidLoad方法。这有用吗？

Answer 1

您可以通过沿着这些行执行某些操作来更改应用程序委托中的字体，但这会更改整个应用程序中的字体，而不是在一个viewcontroller中。

if let customFont = UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20.0) {
    UIBarButtonItem.appearance().setTitleTextAttributes([NSFontAttributeName: customFont], for: .normal)
}

Answer 2

对于Swift 4，你可以在 AppDelegate 中尝试这个。

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        UIBarButtonItem.appearance().setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor.red, NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 15)!], for: UIControlState.normal)

        UIBarButtonItem.appearance().setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor.green, NSAttributedStringKey.font : UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)! ], for: .highlighted)
        UIBarButtonItem.appearance().setTitleTextAttributes([NSAttributedStringKey.foregroundColor: UIColor.blue, NSAttributedStringKey.font : UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)! ], for: .focused)

        return true
}

在 ViewController 。

中

override func viewWillAppear(_ animated: Bool) {

    self.title = "List"
    self.navigationController?.navigationBar.titleTextAttributes = [ NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!]

    // THE BELOW THREE LINES NOT WORKING.

    //navigationItem.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .normal)

    //navigationItem.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .highlighted)

    //navigationItem.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .focused)

}

<强>故事板

<强>输出

Answer 3

而不是：

navigationItem.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .normal)

尝试：

self.navigationController?.navigationBar.topItem?.backBarButtonItem?.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!], for: .normal)

Answer 4

在 Swift 5 中，您可以执行以下操作：

    let attributes = [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 17, weight: .regular)]
    self.navigationItem.backBarButtonItem?.setTitleTextAttributes(attributes, for: .normal)

请注意，它将对下一个推送视图控制器有效，而不是显示屏上的当前视图控制器，这就是为什么它非常令人困惑！

此外，检查情节提要，然后选择上一个视图控制器的导航项，然后在后退按钮（检查器）中键入一些内容。

Answer 5

要使其在 iOS 13.0 上运行，您应该使用 UINavigationBarAppearience。为了更改导航栏中所有元素的字体，您可以执行以下操作：

if #available(iOS 13.0, *) {
    let navBarAppearance = UINavigationBarAppearance()
    let attributes = [NSAttributedStringKey.font: UIFont(name: "AvenirNextCondensed-DemiBoldItalic", size: 20)!]
    navBarAppearance.titleTextAttributes = attributes
    navBarAppearance.buttonAppearance.normal.titleTextAttributes = attributes
    navBarAppearance.doneButtonAppearance.normal.titleTextAttributes = attributes

    self.navigationController?.navigationBar.scrollEdgeAppearance = navBarAppearance
    self.navigationController?.navigationBar.standardAppearance = navBarAppearance
}