I change the size and weight of the UINavigationBar font with the following:

我用以下内容更改了UINavigationBar字体的大小和重量:

UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.black]
UINavigationBar.appearance().titleTextAttributes = [ NSAttributedStringKey.font: UIFont.systemFont(ofSize: 28, weight: .heavy)]

When I present the UIActivityViewController and select Mail, the subject line in the title (not the email) inherits the font change. In order to change this, I change the UINavigationBar back to something smaller.

当我呈现UIActivityViewController并选择Mail时,标题中的主题行(不是电子邮件)继承了字体更改。为了改变这种情况,我将UINavigationBar改回了更小的东西。

While this works, and the subject line in the title is smaller, and now readable, when the UIActivityViewController returns, naturally the UINavigationBar font is still set to the new size and weight. I tried the completion as per below, but the font doesn't resize.

虽然这有效,并且标题中的主题行较小,现在可读,但当UIActivityViewController返回时,UINavigationBar字体仍然设置为新的大小和权重。我尝试按照下面的方式完成,但字体没有调整大小。

@objc func showActivityViewController() {

     UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.black]
     UINavigationBar.appearance().titleTextAttributes = [ NSAttributedStringKey.font: UIFont.systemFont(ofSize: 17, weight: .thin)]

     present(activityViewController, animated: true, completion: {

          UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.black]
          UINavigationBar.appearance().titleTextAttributes = [ NSAttributedStringKey.font: UIFont.systemFont(ofSize: 28, weight: .heavy)]

        })
    }

1 个解决方案

 present(activityViewController, animated: true, completion: {
      DispatchQueue.main.async {
          UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.black]
          UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.font: UIFont.systemFont(ofSize: 28, weight: .heavy)]
      }
 })