NSFontAttributeName 已更改为 String [英] NSFontAttributeName has changed to String

问题描述

我正在尝试正确设置导航栏的样式，我需要将字体更改为大小点为 19 的 Helvetica neue.我曾经使用过此代码，但我注意到现在效果不佳:

i'm trying to style the navigation bar properly, i need to change the font to helvetica neue with a size point of 19. I've ever used this code but i've notice that now doesn't work as well:

navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont(name: "HelveticaNeue-Light", size: 19)]

发生这种情况是因为 NSFontAttributeName 的类型已更改为 String，我已尝试使用

this happens because the type of NSFontAttributeName has changed to String, i've tried to fix it with

navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: "HelveticaNeue-Light, 19"]

但是编译器继续给我一个与字体点大小相关的错误，我该如何解决?

but the compiler continue to give me an error related to point size in font, how can i fix it?

推荐答案

UIFont 构造函数返回一个可选的 (UIFont?)，您必须打开它才能使用.添加 ! 如果你确定你有一个有效的字体名称:

The UIFont constructor is returning an optional (UIFont?) which you must unwrap to use. Add ! if you're sure you have a valid font name:

Swift 4.2:

navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.font: UIFont(name: "HelveticaNeue-Light", size: 19)!]

Swift 4:

navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 19)!]

Swift 3:

navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont(name: "HelveticaNeue-Light", size: 19)!]

注意:如果您在代码中使用静态名称设置字体，那么一旦您确认使用了有效的字体名称，强制展开是安全的.如果您从外部来源(用户或服务器)获取字体名称，您将需要使用可选绑定，例如 if let font = UIFont(... 或 guard let font = UIFont(... 以在使用前安全地解开字体.

Note: If you are setting a font with a static name in your code, then force unwrapping is safe once you’ve verified you’re using a valid font name. If you are getting the font name from an external source (the user or a server), you will want to use optional binding such as if let font = UIFont(... or guard let font = UIFont(... to safely unwrap the font before use.

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