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如何在iOS7中使用自定义字体和动态文本大小

iosios7
88

iOS7中有新的API可以获取根据用户设置的偏好自动调整字体大小的字体。

使用它看起来像这样：

UIFont *myFont = [UIFont fontWithDescriptor:[UIFontDescriptor preferredFontDescriptorWithTextStyle:UIFontTextStyleHeadline] size:0];

现在，无论您将此文本分配给何处，都会随着用户更改其系统文本大小设置而上下移动字体大小。(记得侦听name:UIContentSizeCategoryDidChangeNotification通知并更新您的视图以适应大小的更改)。

如果我想使用除默认Helvetica-Neue之外的其他字体，该怎么办？

从iOS 11+开始，苹果支持使用自定义动态字体大小。有关实现，请参阅此答案。 - Umair Ali
12个回答
132
在该API背后，苹果有某种查找表，返回特定的字体系列、大小和有时候的符号特征（如粗体），例如 UIFontTextStyleHeadline 以及用户首选的文本大小。后者是从sharedApplication获取的字符串，如下所示：
[UIApplication sharedApplication].preferredContentSizeCategory;

我记录了Helvetica-Neue的各种动态文本大小的所有默认大小/字体/特征(请参阅此链接)。我们后来添加了对可访问性大小的处理，这很重要。
因此，你只需要构建一个类似的查找表。我们的设计师为我创建了一个简单的电子表格：
请注意，我们添加了几个风格(caption 3&4)，以便有8个而不是6个可供选择。
然后，您需要将其放在方便的位置，例如UIFontDescriptor的类别中。您的方法应该返回一个UIFontDescriptor，就像苹果的API那样，这样仍然很容易通过符号特征等进行调整。
我的类别如下所示：
UIFontDescriptor+AvenirNext.h
#import <UIKit/UIKit.h>

extern NSString *const ANUIFontTextStyleCaption3;

@interface UIFontDescriptor (AvenirNext)

+(UIFontDescriptor *)preferredAvenirNextFontDescriptorWithTextStyle:(NSString *)style;

@end

UIFontDescriptor+AvenirNext.m

#import "UIFontDescriptor+AvenirNext.h"

NSString *const ANUIFontTextStyleCaption3 = @"ANUIFontTextStyleCaption3";
NSString *const ANUIFontTextStyleCaption4 = @"ANUIFontTextStyleCaption4";

@implementation UIFontDescriptor (AvenirNext)
+(UIFontDescriptor *)preferredAvenirNextFontDescriptorWithTextStyle:(NSString *)style {
    static dispatch_once_t onceToken;
    static NSDictionary *fontSizeTable;
    dispatch_once(&onceToken, ^{
        fontSizeTable = @{
          UIFontTextStyleHeadline: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @26,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @25,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @24,
                                    UIContentSizeCategoryAccessibilityLarge: @24,
                                    UIContentSizeCategoryAccessibilityMedium: @23,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @23,
                                    UIContentSizeCategoryExtraExtraLarge: @22,
                                    UIContentSizeCategoryExtraLarge: @21,
                                    UIContentSizeCategoryLarge: @20,
                                    UIContentSizeCategoryMedium: @19,
                                    UIContentSizeCategorySmall: @18,
                                    UIContentSizeCategoryExtraSmall: @17,},

       UIFontTextStyleSubheadline: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @24,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @23,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @22,
                                    UIContentSizeCategoryAccessibilityLarge: @22,
                                    UIContentSizeCategoryAccessibilityMedium: @21,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @21,
                                    UIContentSizeCategoryExtraExtraLarge: @20,
                                    UIContentSizeCategoryExtraLarge: @19,
                                    UIContentSizeCategoryLarge: @18,
                                    UIContentSizeCategoryMedium: @17,
                                    UIContentSizeCategorySmall: @16,
                                    UIContentSizeCategoryExtraSmall: @15,},

              UIFontTextStyleBody: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @21,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @20,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @19,
                                    UIContentSizeCategoryAccessibilityLarge: @19,
                                    UIContentSizeCategoryAccessibilityMedium: @18,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @18,
                                    UIContentSizeCategoryExtraExtraLarge: @17,
                                    UIContentSizeCategoryExtraLarge: @16,
                                    UIContentSizeCategoryLarge: @15,
                                    UIContentSizeCategoryMedium: @14,
                                    UIContentSizeCategorySmall: @13,
                                    UIContentSizeCategoryExtraSmall: @12,},
          
          UIFontTextStyleCaption1: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @19,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @18,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @17,
                                    UIContentSizeCategoryAccessibilityLarge: @17,
                                    UIContentSizeCategoryAccessibilityMedium: @16,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @16,
                                    UIContentSizeCategoryExtraExtraLarge: @16,
                                    UIContentSizeCategoryExtraLarge: @15,
                                    UIContentSizeCategoryLarge: @14,
                                    UIContentSizeCategoryMedium: @13,
                                    UIContentSizeCategorySmall: @12,
                                    UIContentSizeCategoryExtraSmall: @12,},
          
          UIFontTextStyleCaption2: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @18,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @17,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @16,
                                    UIContentSizeCategoryAccessibilityLarge: @16,
                                    UIContentSizeCategoryAccessibilityMedium: @15,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @15,
                                    UIContentSizeCategoryExtraExtraLarge: @14,
                                    UIContentSizeCategoryExtraLarge: @14,
                                    UIContentSizeCategoryLarge: @13,
                                    UIContentSizeCategoryMedium: @12,
                                    UIContentSizeCategorySmall: @12,
                                    UIContentSizeCategoryExtraSmall: @11,},
          
        ANUIFontTextStyleCaption3: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @17,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @16,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @15,
                                    UIContentSizeCategoryAccessibilityLarge: @15,
                                    UIContentSizeCategoryAccessibilityMedium: @14,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @14,
                                    UIContentSizeCategoryExtraExtraLarge: @13,
                                    UIContentSizeCategoryExtraLarge: @12,
                                    UIContentSizeCategoryLarge: @12,
                                    UIContentSizeCategoryMedium: @12,
                                    UIContentSizeCategorySmall: @11,
                                    UIContentSizeCategoryExtraSmall: @10,},

          UIFontTextStyleFootnote: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @16,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @15,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @14,
                                    UIContentSizeCategoryAccessibilityLarge: @14,
                                    UIContentSizeCategoryAccessibilityMedium: @13,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @13,
                                    UIContentSizeCategoryExtraExtraLarge: @12,
                                    UIContentSizeCategoryExtraLarge: @12,
                                    UIContentSizeCategoryLarge: @11,
                                    UIContentSizeCategoryMedium: @11,
                                    UIContentSizeCategorySmall: @10,
                                    UIContentSizeCategoryExtraSmall: @10,},

          ANUIFontTextStyleCaption4: @{
                                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: @15,
                                    UIContentSizeCategoryAccessibilityExtraExtraLarge: @14,
                                    UIContentSizeCategoryAccessibilityExtraLarge: @13,
                                    UIContentSizeCategoryAccessibilityLarge: @13,
                                    UIContentSizeCategoryAccessibilityMedium: @12,
                                    UIContentSizeCategoryExtraExtraExtraLarge: @12,
                                    UIContentSizeCategoryExtraExtraLarge: @11,
                                    UIContentSizeCategoryExtraLarge: @11,
                                    UIContentSizeCategoryLarge: @10,
                                    UIContentSizeCategoryMedium: @10,
                                    UIContentSizeCategorySmall: @9,
                                    UIContentSizeCategoryExtraSmall: @9,},
        };
    });
    
    
    NSString *contentSize = [UIApplication sharedApplication].preferredContentSizeCategory;
    return [UIFontDescriptor fontDescriptorWithName:[self preferredFontName] size:((NSNumber *)fontSizeTable[style][contentSize]).floatValue];
}
+(UIFontDescriptor *)preferredAvenirNextDemiBoldFontDescriptorWithTextStyle:(NSString *)style {
    return [[self preferredAvenirNextFontDescriptorWithTextStyle:style] fontDescriptorWithSymbolicTraits:UIFontDescriptorTraitBold];
}

+(UIFontDescriptor *)preferredAvenirNextBoldFontDescriptorWithTextStyle:(NSString *)style {
    return [UIFontDescriptor fontDescriptorWithName:[self preferredBoldFontName] size:[self preferredAvenirNextFontDescriptorWithTextStyle:style].pointSize];
}

+(NSString *)preferredFontName {
    return @"AvenirNext-Medium";
}
+(NSString *)preferredBoldFontName {
    return @"AvenirNext-Bold";
}

@end

我们选择使用相同的基础字体AvenirNext-Medium，然后通过符号特征加粗等，但是如果您想要的话，也可以在查找表中指定不同的字重变体，例如AvenirNext-ExtraBold。

就是这样了！我们像这样使用它：

[UIFont fontWithDescriptor:[UIFontDescriptor preferredAvenirNextFontDescriptorWithTextStyle:UIFontTextStyleHeadline] size: 0]
6
优秀的解决方案，但是你忽略了可访问性常量：UIContentSizeCategoryAccessibilityMedium、UIContentSizeCategoryAccessibilityLarge等。 - Ben Jackson
1
为什么不扩展UIFont，这样您就可以直接使用：[UIFont preferredAvenirFontForTextStyle:UIFontTextStyleHeadline]？在您在底部给出的示例中，大小是多余的吗？ - cleverbit
2
@richarddas 只是为了保持与苹果的模式一致。大小为0将被忽略，并从描述符中直接传递正确的大小。 - Bob Spryn
嗨，我正在使用Xcode 6.0.1。我使用上面的代码为标签设置自定义字体。然而，我能在Interface Builder中找到自定义字体，但无法通过此代码应用。我使用了Sansation字体文件。请帮助我。谢谢。 - Nikhil Lihla
4
从iOS 8.4开始，苹果微调了字体大小： https://gist.github.com/klaas/750f489e2390389ab812 - Klaas
显示剩余7条评论
15

这是我在Swift中的实现方式。我喜欢它，因为它更通用，只需要一个表格，并且应该适用于任何字体。首先，我编写了一个通用的乘数（在getter中）。

var fontSizeMultiplier : CGFloat {
    get {
        switch UIApplication.sharedApplication().preferredContentSizeCategory {
        case UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: return 23 / 16
        case UIContentSizeCategoryAccessibilityExtraExtraLarge: return 22 / 16
        case UIContentSizeCategoryAccessibilityExtraLarge: return 21 / 16
        case UIContentSizeCategoryAccessibilityLarge: return 20 / 16
        case UIContentSizeCategoryAccessibilityMedium: return 19 / 16
        case UIContentSizeCategoryExtraExtraExtraLarge: return 19 / 16
        case UIContentSizeCategoryExtraExtraLarge: return 18 / 16
        case UIContentSizeCategoryExtraLarge: return 17 / 16
        case UIContentSizeCategoryLarge: return 1.0
        case UIContentSizeCategoryMedium: return 15 / 16
        case UIContentSizeCategorySmall: return 14 / 16
        case UIContentSizeCategoryExtraSmall: return 13 / 16
        default: return 1.0
        }
    }
}

然后我使用类似这样的UIFontDescriptor更新字体（例如在观察者中）：

textView.font = UIFont(descriptor: fontDescriptor!, size: fontDescriptor!.pointSize * fontSizeMultiplier)
这样做不行，因为每次在设置中更新大小时，pointSize 将呈指数增长。如果您设置默认字体大小，则可以将其用作基础，并将其乘以 fontSizeMultiplier。 - TejAces
@TejAces - 这个很好用。我已经使用了多年。由于它返回的是字面值，我不明白你为什么认为更改设置会增加它的大小。 - Bill Weinman
13

iOS 11引入了UIFontMetrics类。为您感兴趣的文本样式创建FontMetrics对象。然后选择任何字体，大小为标准动态类型大小。然后，您可以要求FontMetrics对象根据用户当前设置来缩放该字体。

let bodyMetrics = UIFontMetrics(forTextStyle: .body)
let standardFont = ... // any font you want, for standard type size
let font = bodyMetrics.scaledFont(for: standardFont)
8

@Bob Spryn的代码已使用Swift重写：

import UIKit

extension UIFontDescriptor {

    private struct SubStruct {
        static var preferredFontName: NSString = "OEMeodedPashutPro-Regular"
    }

    class func preferredDescriptor(textStyle: NSString) -> UIFontDescriptor {
        struct Static {
            static var onceToken : dispatch_once_t = 0
            static var fontSizeTable : NSDictionary = NSDictionary()
        }

        dispatch_once(&Static.onceToken) {
            Static.fontSizeTable = [
                UIFontTextStyleHeadline: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 26,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 25,
                    UIContentSizeCategoryAccessibilityExtraLarge: 24,
                    UIContentSizeCategoryAccessibilityLarge: 24,
                    UIContentSizeCategoryAccessibilityMedium: 23,
                    UIContentSizeCategoryExtraExtraExtraLarge: 23,
                    UIContentSizeCategoryExtraExtraLarge: 22,
                    UIContentSizeCategoryExtraLarge: 21,
                    UIContentSizeCategoryLarge: 20,
                    UIContentSizeCategoryMedium: 19,
                    UIContentSizeCategorySmall: 18,
                    UIContentSizeCategoryExtraSmall: 17
                ],
                UIFontTextStyleSubheadline: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 24,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 23,
                    UIContentSizeCategoryAccessibilityExtraLarge: 22,
                    UIContentSizeCategoryAccessibilityLarge: 22,
                    UIContentSizeCategoryAccessibilityMedium: 21,
                    UIContentSizeCategoryExtraExtraExtraLarge: 21,
                    UIContentSizeCategoryExtraExtraLarge: 20,
                    UIContentSizeCategoryExtraLarge: 19,
                    UIContentSizeCategoryLarge: 18,
                    UIContentSizeCategoryMedium: 17,
                    UIContentSizeCategorySmall: 16,
                    UIContentSizeCategoryExtraSmall: 15
                ],
                UIFontTextStyleBody: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 21,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 20,
                    UIContentSizeCategoryAccessibilityExtraLarge: 19,
                    UIContentSizeCategoryAccessibilityLarge: 19,
                    UIContentSizeCategoryAccessibilityMedium: 18,
                    UIContentSizeCategoryExtraExtraExtraLarge: 18,
                    UIContentSizeCategoryExtraExtraLarge: 17,
                    UIContentSizeCategoryExtraLarge: 16,
                    UIContentSizeCategoryLarge: 15,
                    UIContentSizeCategoryMedium: 14,
                    UIContentSizeCategorySmall: 13,
                    UIContentSizeCategoryExtraSmall: 12
                ],
                UIFontTextStyleCaption1: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 19,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 18,
                    UIContentSizeCategoryAccessibilityExtraLarge: 17,
                    UIContentSizeCategoryAccessibilityLarge: 17,
                    UIContentSizeCategoryAccessibilityMedium: 16,
                    UIContentSizeCategoryExtraExtraExtraLarge: 16,
                    UIContentSizeCategoryExtraExtraLarge: 16,
                    UIContentSizeCategoryExtraLarge: 15,
                    UIContentSizeCategoryLarge: 14,
                    UIContentSizeCategoryMedium: 13,
                    UIContentSizeCategorySmall: 12,
                    UIContentSizeCategoryExtraSmall: 12
                ],
                UIFontTextStyleCaption2: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 18,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 17,
                    UIContentSizeCategoryAccessibilityExtraLarge: 16,
                    UIContentSizeCategoryAccessibilityLarge: 16,
                    UIContentSizeCategoryAccessibilityMedium: 15,
                    UIContentSizeCategoryExtraExtraExtraLarge: 15,
                    UIContentSizeCategoryExtraExtraLarge: 14,
                    UIContentSizeCategoryExtraLarge: 14,
                    UIContentSizeCategoryLarge: 13,
                    UIContentSizeCategoryMedium: 12,
                    UIContentSizeCategorySmall: 12,
                    UIContentSizeCategoryExtraSmall: 11
                ],
                UIFontTextStyleFootnote: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 16,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 15,
                    UIContentSizeCategoryAccessibilityExtraLarge: 14,
                    UIContentSizeCategoryAccessibilityLarge: 14,
                    UIContentSizeCategoryAccessibilityMedium: 13,
                    UIContentSizeCategoryExtraExtraExtraLarge: 13,
                    UIContentSizeCategoryExtraExtraLarge: 12,
                    UIContentSizeCategoryExtraLarge: 12,
                    UIContentSizeCategoryLarge: 11,
                    UIContentSizeCategoryMedium: 11,
                    UIContentSizeCategorySmall: 10,
                    UIContentSizeCategoryExtraSmall: 10
                ],
            ]
        }

        let contentSize = UIApplication.sharedApplication().preferredContentSizeCategory

        let style = Static.fontSizeTable[textStyle] as NSDictionary

        return UIFontDescriptor(name: SubStruct.preferredFontName, size: CGFloat((style[contentSize] as NSNumber).floatValue))
    }

}

使用方法：

UIFont(descriptor: UIFontDescriptor.preferredDescriptor(UIFontTextStyleBody), size: 0)
1
Xcode 7.2让我改变了最后两行代码：let style = Static.fontSizeTable[textStyle] as! NSDictionary 和 return UIFontDescriptor(name: SubStruct.preferredFontName as String, size: CGFloat((style[contentSize] as! NSNumber).floatValue))。 - koen
如果我能做一些可以在Storyboard中显示首选字体的东西，那将非常酷。也许通过子类化文本元素实现。 - Aaron Bratcher
7

试试这个：

UIFontDescriptor *userHeadLineFont = [UIFontDescriptor preferredFontDescriptorWithTextStyle:UIFontTextStyleHeadline];
CGFloat userHeadLineFontSize = [userHeadLineFont pointSize];
myFont = [UIFont fontWithName:@"Baskerville" size:userHeadLineFontSize];

请记住，这段代码只是一个近似值（动态类型远不止缩放字体大小）。

你能详细说明一下括号吗？除了缩放之外，我还需要考虑什么？ - hfossli
2
字体“动态类型”和实际使用的字体之间存在映射关系。例如，小号字体可以变成粗体。我不知道具体的映射关系。请查看这篇文章中的最后一张图片（“动态类型光学缩放”）以更好地理解：http://fireballed.org/linked/2013/07/08/ios-7-type/。 - valfer
1
这个解决方案与已批准的正确答案相同，但行数有点不同。非常好的解决方案。在SWIFT中也是一样的。https://dev59.com/mFsW5IYBdhLWcg3wI0RH - Vanya
这是一篇由@valfer在评论中提及的文章的可用链接: 《超越Helvetica: iOS 7字体背后真正的故事》(Beyond Helvetica: The Real Story Behind Fonts in iOS 7)。 - 0xced
6
与 @bill-weinman 的方法类似，我将比例尺分解为一个不依赖于给定字体大小为16的函数。
/// The font scale for a given font size.
///
/// - seealso: [Source](https://dev59.com/zmIj5IYBdhLWcg3wNyn1#33114525)
///
/// - Parameter fontSize: The font size.
/// - Returns: The font scale
public func fontScale(for fontSize: CGFloat) -> CGFloat {
    switch UIApplication.shared.preferredContentSizeCategory {
    case UIContentSizeCategory.accessibilityExtraExtraExtraLarge:    return (fontSize + 8) / fontSize
    case UIContentSizeCategory.accessibilityExtraExtraLarge:         return (fontSize + 7) / fontSize
    case UIContentSizeCategory.accessibilityExtraLarge:              return (fontSize + 6) / fontSize
    case UIContentSizeCategory.accessibilityLarge:                   return (fontSize + 5) / fontSize
    case UIContentSizeCategory.accessibilityMedium:                  return (fontSize + 4) / fontSize
    case UIContentSizeCategory.extraExtraExtraLarge:                 return (fontSize + 3) / fontSize
    case UIContentSizeCategory.extraExtraLarge:                      return (fontSize + 2) / fontSize
    case UIContentSizeCategory.extraLarge:                           return (fontSize + 1) / fontSize
    case UIContentSizeCategory.large:                                return 1.0
    case UIContentSizeCategory.medium:                               return (fontSize - 1) / fontSize
    case UIContentSizeCategory.small:                                return (fontSize - 2) / fontSize
    case UIContentSizeCategory.extraSmall:                           return (fontSize - 3) / fontSize
    default:
        return 1.0
    }
}

然后可以像这样与自定义字体一起使用：

/// Light font of specified size.
///
/// - Parameter size: Font size.
/// - Returns: Light font of specified size.
func lightFont(ofSize size: CGFloat) -> UIFont {
    let scaledSize = size * fontScale(for: size)

    return UIFont(name: "HelveticaNeueLTStd-Lt", size: scaledSize)!
}
如果你处在不想要微调一切的阶段，那么这并不算太糟。 并且，如果你的自定义字体相对较小，需要默认进行一些缩放。 - JanMensch
FYI - 我的方法不依赖于字体大小。它基于比例返回一个值。它可以很好地处理自定义/缩放字体。 - Bill Weinman
3
在iOS 11中，您可以使用：
var customFont = UIFont.systemFont(ofSize: 17.0)
if #available(iOS 11.0, *) {
    customFont = UIFontMetrics.default.scaledFont(for: customFont)
}
// use customFont...

另请参阅使用动态类型构建应用程序 WWDC 2017 - Session 245 - iOS，时间为8:34。

2

基于 @smartDonkey 对 @Bob Spryn 代码的移植而来的 Swift 2.1-3.0 代码。同时，还更新了来自@Klaas的苹果尺寸。

import UIKit

extension UIFontDescriptor {

    private struct SubStruct {
        static var preferredFontName: String = "Roboto-Light"
    }

    class func preferredDescriptor(textStyle: NSString) -> UIFontDescriptor {
        struct Static {
            static var onceToken : dispatch_once_t = 0
            static var fontSizeTable : NSDictionary = NSDictionary()
        }

        dispatch_once(&Static.onceToken) {
            Static.fontSizeTable = [
                UIFontTextStyleHeadline: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 23,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 23,
                    UIContentSizeCategoryAccessibilityExtraLarge: 23,
                    UIContentSizeCategoryAccessibilityLarge: 23,
                    UIContentSizeCategoryAccessibilityMedium: 23,
                    UIContentSizeCategoryExtraExtraExtraLarge: 23,
                    UIContentSizeCategoryExtraExtraLarge: 21,
                    UIContentSizeCategoryExtraLarge: 19,
                    UIContentSizeCategoryLarge: 17,
                    UIContentSizeCategoryMedium: 16,
                    UIContentSizeCategorySmall: 15,
                    UIContentSizeCategoryExtraSmall: 14
                ],
                UIFontTextStyleSubheadline: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 21,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 21,
                    UIContentSizeCategoryAccessibilityExtraLarge: 21,
                    UIContentSizeCategoryAccessibilityLarge: 21,
                    UIContentSizeCategoryAccessibilityMedium: 21,
                    UIContentSizeCategoryExtraExtraExtraLarge: 21,
                    UIContentSizeCategoryExtraExtraLarge: 19,
                    UIContentSizeCategoryExtraLarge: 17,
                    UIContentSizeCategoryLarge: 15,
                    UIContentSizeCategoryMedium: 14,
                    UIContentSizeCategorySmall: 13,
                    UIContentSizeCategoryExtraSmall: 12
                ],
                UIFontTextStyleBody: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 53,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 47,
                    UIContentSizeCategoryAccessibilityExtraLarge: 40,
                    UIContentSizeCategoryAccessibilityLarge: 33,
                    UIContentSizeCategoryAccessibilityMedium: 28,
                    UIContentSizeCategoryExtraExtraExtraLarge: 23,
                    UIContentSizeCategoryExtraExtraLarge: 21,
                    UIContentSizeCategoryExtraLarge: 19,
                    UIContentSizeCategoryLarge: 17,
                    UIContentSizeCategoryMedium: 16,
                    UIContentSizeCategorySmall: 15,
                    UIContentSizeCategoryExtraSmall: 14
                ],
                UIFontTextStyleCaption1: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 18,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 18,
                    UIContentSizeCategoryAccessibilityExtraLarge: 18,
                    UIContentSizeCategoryAccessibilityLarge: 18,
                    UIContentSizeCategoryAccessibilityMedium: 18,
                    UIContentSizeCategoryExtraExtraExtraLarge: 18,
                    UIContentSizeCategoryExtraExtraLarge: 16,
                    UIContentSizeCategoryExtraLarge: 14,
                    UIContentSizeCategoryLarge: 12,
                    UIContentSizeCategoryMedium: 11,
                    UIContentSizeCategorySmall: 11,
                    UIContentSizeCategoryExtraSmall: 11
                ],
                UIFontTextStyleCaption2: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 17,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 17,
                    UIContentSizeCategoryAccessibilityExtraLarge: 17,
                    UIContentSizeCategoryAccessibilityLarge: 17,
                    UIContentSizeCategoryAccessibilityMedium: 17,
                    UIContentSizeCategoryExtraExtraExtraLarge: 17,
                    UIContentSizeCategoryExtraExtraLarge: 15,
                    UIContentSizeCategoryExtraLarge: 13,
                    UIContentSizeCategoryLarge: 11,
                    UIContentSizeCategoryMedium: 11,
                    UIContentSizeCategorySmall: 11,
                    UIContentSizeCategoryExtraSmall: 11
                ],
                UIFontTextStyleFootnote: [
                    UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: 19,
                    UIContentSizeCategoryAccessibilityExtraExtraLarge: 19,
                    UIContentSizeCategoryAccessibilityExtraLarge: 19,
                    UIContentSizeCategoryAccessibilityLarge: 19,
                    UIContentSizeCategoryAccessibilityMedium: 19,
                    UIContentSizeCategoryExtraExtraExtraLarge: 19,
                    UIContentSizeCategoryExtraExtraLarge: 17,
                    UIContentSizeCategoryExtraLarge: 15,
                    UIContentSizeCategoryLarge: 13,
                    UIContentSizeCategoryMedium: 12,
                    UIContentSizeCategorySmall: 12,
                    UIContentSizeCategoryExtraSmall: 12
                ],
            ]
        }

        let contentSize = UIApplication.sharedApplication().preferredContentSizeCategory
        let style = Static.fontSizeTable[textStyle] as! NSDictionary
        return UIFontDescriptor(name: SubStruct.preferredFontName, size: CGFloat((style[contentSize] as! NSNumber).floatValue))
    }

}
您的解决方案在Swift 3上出现错误：'dispatch_once_t'在Swift中不可用：请改用惰性初始化全局变量。 - thexande
2

以下是我对 @Gobe 的答案的看法，使用 Swift 3：

extension UIFontDescriptor {

@nonobjc static var fontSizeTable: [UIFontTextStyle : [UIContentSizeCategory : CGFloat]] = {
    return [
        .headline: [
            .accessibilityExtraExtraExtraLarge: 23,
            .accessibilityExtraExtraLarge: 23,
            .accessibilityExtraLarge: 23,
            .accessibilityLarge: 23,
            .accessibilityMedium: 23,
            .extraExtraExtraLarge: 23,
            .extraExtraLarge: 21,
            .extraLarge: 19,
            .large: 17,
            .medium: 16,
            .small: 15,
            .extraSmall: 14],
        .subheadline: [
            .accessibilityExtraExtraExtraLarge: 21,
            .accessibilityExtraExtraLarge: 21,
            .accessibilityExtraLarge: 21,
            .accessibilityLarge: 21,
            .accessibilityMedium: 21,
            .extraExtraExtraLarge: 21,
            .extraExtraLarge: 19,
            .extraLarge: 17,
            .large: 15,
            .medium: 14,
            .small: 13,
            .extraSmall: 12],
        .body: [
            .accessibilityExtraExtraExtraLarge: 53,
            .accessibilityExtraExtraLarge: 47,
            .accessibilityExtraLarge: 40,
            .accessibilityLarge: 33,
            .accessibilityMedium: 28,
            .extraExtraExtraLarge: 23,
            .extraExtraLarge: 21,
            .extraLarge: 19,
            .large: 17,
            .medium: 16,
            .small: 15,
            .extraSmall: 14],
        .caption1: [
            .accessibilityExtraExtraExtraLarge: 18,
            .accessibilityExtraExtraLarge: 18,
            .accessibilityExtraLarge: 18,
            .accessibilityLarge: 18,
            .accessibilityMedium: 18,
            .extraExtraExtraLarge: 18,
            .extraExtraLarge: 16,
            .extraLarge: 14,
            .large: 12,
            .medium: 11,
            .small: 11,
            .extraSmall: 11],
        .caption2: [
            .accessibilityExtraExtraExtraLarge: 17,
            .accessibilityExtraExtraLarge: 17,
            .accessibilityExtraLarge: 17,
            .accessibilityLarge: 17,
            .accessibilityMedium: 17,
            .extraExtraExtraLarge: 17,
            .extraExtraLarge: 15,
            .extraLarge: 13,
            .large: 11,
            .medium: 11,
            .small: 11,
            .extraSmall: 11],
        .footnote: [
            .accessibilityExtraExtraExtraLarge: 19,
            .accessibilityExtraExtraLarge: 19,
            .accessibilityExtraLarge: 19,
            .accessibilityLarge: 19,
            .accessibilityMedium: 19,
            .extraExtraExtraLarge: 19,
            .extraExtraLarge: 17,
            .extraLarge: 15,
            .large: 13,
            .medium: 12,
            .small: 12,
            .extraSmall: 12],
    ]
}()

class func currentPreferredSize(textStyle: UIFontTextStyle = .body) -> CGFloat {
    let contentSize = UIApplication.shared.preferredContentSizeCategory
    guard let style = fontSizeTable[textStyle], let fontSize = style[contentSize] else { return 17 }
    return fontSize
}

class func preferredFontDescriptor(fontName: String = "SnellRoundhand", textStyle: UIFontTextStyle = .body) -> UIFontDescriptor {
    return UIFontDescriptor(name: fontName, size: currentPreferredSize())
}
}
Swift5版本已添加到https://dev59.com/qlgR5IYBdhLWcg3wDJtN#64236722 - marika.daboja
1
这是我更新preferredFontForTextStyle字体的方法：
UIFont *font = [UIFont preferredFontForTextStyle:UIFontTextStyleBody];
UIFontDescriptor *fontDesc = [font fontDescriptor];
fontDesc = [fontDesc fontDescriptorByAddingAttributes:@{UIFontDescriptorNameAttribute : @"Helvetica",
                                                        UIFontDescriptorSizeAttribute : @16}];

font = [UIFont fontWithDescriptor:fontDesc
                             size:[fontDesc pointSize]];
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