ios 如何以编程方式访问iOS系统字体
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How to access the iOS system font programmatically
提问by zevij
I am trying to change the font size of the title of a navigation bar. I know I can set its attributes using:
我正在尝试更改导航栏标题的字体大小。我知道我可以使用以下方法设置其属性：
var attributes = [ NSForegroundColorAttributeName: UIColor.blackColor(), NSFontAttributeName: UIFont(name: "the font name", size: 18)! ]
...
...
self.navigationController?.navigationBar.titleTextAttributes = attributes
What I cannot seem to find is the correct 'System' font name.
我似乎找不到正确的“系统”字体名称。
I was after the default, a.k.a System, font name. I tried printing all the available fonts only to discover it does not belong to a family and does not seem to have an explicit name.
我追求的是默认的，也就是系统，字体名称。我尝试打印所有可用的字体，结果发现它不属于一个系列，并且似乎没有明确的名称。
回答by Roland Keesom
I think you need:
我认为你需要：
NSFontAttributeName : UIFont.systemFontOfSize(19.0)
Or the bold version:
或者粗体版本：
NSFontAttributeName : UIFont.boldSystemFontOfSize(19.0)
See this guidefor more info on user interface guidelines and fonts.
有关用户界面指南和字体的更多信息，请参阅本指南。
回答by Philippe
You can access the system font like this, and even set the weight of the font:
您可以像这样访问系统字体，甚至可以设置字体的粗细：
UIFont.systemFont(ofSize: 18, weight: UIFontWeightLight)UIFont.systemFontOfSize(18, weight: UIFontWeightLight)
UIFont.systemFont(ofSize: 18, weight: UIFontWeightLight)UIFont.systemFontOfSize(18, weight: UIFontWeightLight)
For the font weight you have the choice between those constants, there available from iOS 8.2:
对于字体粗细，您可以在这些常量之间进行选择，可从iOS 8.2 获得：
UIFontWeightUltraLight,
UIFontWeightThin,
UIFontWeightLight,
UIFontWeightRegular,
UIFontWeightMedium,
UIFontWeightSemibold,
UIFontWeightBold,
UIFontWeightHeavy,
UIFontWeightBlack
回答by Maksim Kniazev
SWIFT 4: shorter version
SWIFT 4：较短的版本
UIFont.systemFont(ofSize: 50.0, weight: .regular)
回答by Vincent
(In line with the answer from Philippe for the latest version)
（与 Philippe 对最新版本的回答一致）
Swift 4
UIFont.systemFont(ofSize: 18, weight: UIFont.Weight.light)
斯威夫特 4
UIFont.systemFont(ofSize: 18, weight: UIFont.Weight.light)
回答by Sujith Chandran
self.navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName : UIFont.systemFontOfSize(6)]
回答by miche.atucha
Just use methods of UIFont (swift):
只需使用 UIFont (swift) 的方法：
let sysFont: UIFont = UIFont.systemFontOfSize(UIFont.systemFontSize())
Hope it helps!
希望能帮助到你！
回答by Aditi Agrawal
Try the below code:
试试下面的代码：
self.navigationController!.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont(name:"Arial", size:14.0)!, NSForegroundColorAttributeName:UIColor.blackColor()]
回答by Amirreza
Besides all the answers, it's a better idea to use system font with system styles instead of defining custom sizes and weights. To access them programmatically, for example for the headline, you can use this method:
除了所有答案之外，最好将系统字体与系统样式一起使用，而不是定义自定义大小和粗细。要以编程方式访问它们，例如标题，您可以使用以下方法：
let font = UIFont.preferredFont(forTextStyle: .headline)
I know it is a valid code at least for Swift 5.
我知道至少对于 Swift 5 来说这是一个有效的代码。
