如何在 iOS7中使用具有动态文本大小的自定义字体

在 iOS7中，有一些新的 API 用于获得一种字体，这种字体可以自动调整到用户在其首选项中设置的文本大小。

它看起来像这样使用它:

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

现在，无论您分配给它的文本是什么，它都会随着用户更改系统文本大小设置而在字体大小上下移动。(记住听取 name:UIContentSizeCategoryDidChangeNotification通知并更新视图以说明尺寸的变化)。

如何使用不是默认 Helvetica-Neue 字体的动态文本？

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最佳答案

Behind the scenes of that API, apple has some sort of lookup table that returns a specific font family, size, and sometimes symbolic traits (like bold) that (e.g. UIFontTextStyleHeadline) and the user's preferred text size. The latter is a string pulled off of the sharedApplication like this:

[UIApplication sharedApplication].preferredContentSizeCategory;

(I logged out all the default sizes/fonts/traits for Helvetica-Neue for the various dynamic text sizes). We've since added handling for the accessibility sizes, which is important.

So all you really have to do is build a similar lookup table. Our designer created a simple spreadsheet for me:

Font size lookup table

Notice that we added a couple styles (caption 3 & 4) to have 8 instead of 6 to choose from.

Then you'll want to put it someplace convenient, like a category on UIFontDescriptor. You'll want your method to return a UIFontDescriptor like Apple's API, so that it's still easy to adjust with symbolic traits, etc.

My category looks like this:

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

We chose to use the same base font AvenirNext-Medium, and then bold and such via symbolic traits, but you could get crazy and specify different weight variants on your font as part of your lookup table as well if you wanted, like AvenirNext-ExtraBold.

That's all there is to it! We use it like this:

[UIFont fontWithDescriptor:[UIFontDescriptor preferredAvenirNextFontDescriptorWithTextStyle:UIFontTextStyleHeadline] size: 0]
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Try this:

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

But keep in mind that this code is only an approximation (Dynamic Type does much more than just scale font size).

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This is how I update the font of a prefferedFontForTextStyle:

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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@Bob Spryn code rewritten with swift:

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))
}


}

Usage:

UIFont(descriptor: UIFontDescriptor.preferredDescriptor(UIFontTextStyleBody), size: 0)
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This is how I do it in Swift. I like this because it's more general, it only requires one table, and it should work well with any font. First I wrote a generalized multiplier (in a getter). 

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
}
}
}

Then I update the font (e.g., in the observer) using a UIFontDescriptor like this: 

textView.font = UIFont(descriptor: fontDescriptor!, size: fontDescriptor!.pointSize * fontSizeMultiplier)
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Just wanted to jump in and say that there's a library out there to help integrate custom fonts and deal with the Dynamic Type size changes. It's called, helpfully, Font (https://github.com/adamyanalunas/Font) and instead of being a magic solution it sets up a structure for handling each custom font differently while removing the boilerplate.

n.b. I'm the author of this lil' library and I think it's neat.

小开

Swift 2.1-3.0 code based on @smartDonkey's port of @Bob Spryn code. Also updated with the Apple sizes from @Klaas.

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))
}


}
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Here is my take on @Gobe's answer, in 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())
}
}
小开

Similar to @bill-weinman's approach, I took the scales, and broke it out into a function that doesn't rely on a given font size of 16.

/// The font scale for a given font size.
///
/// - seealso: [Source](https://stackoverflow.com/a/33114525/3643020)
///
/// - 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
}
}

It can then be used with custom fonts like this:

/// 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)!
}
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In iOS 11 UIFontMetrics class was introduced. Create a FontMetrics object for the text style that you're interested in. Then choose any font you want, sized for the standard dynamic type size. And then you can ask the FontMetrics object to scale that font given the user's current settings.

let bodyMetrics = UIFontMetrics(forTextStyle: .body)
let standardFont = ... // any font you want, for standard type size
let font = bodyMetrics.scaledFont(for: standardFont)
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In iOS 11 you can use:

var customFont = UIFont.systemFont(ofSize: 17.0)
if #available(iOS 11.0, *) {
customFont = UIFontMetrics.default.scaledFont(for: customFont)
}
// use customFont...

See also Building Apps with Dynamic Type WWDC 2017 - Session 245 - iOS time 8:34.

小开

Starting from iOS 11 you can programmatically adjust custom fonts configured in visual editor:

  1. Configure your custom font using visual editor
  2. Adjust font size in viewDidLoad method:
@IBOutlet weak var leftLangLabel: UILabel!


override func viewDidLoad() {
super.viewDidLoad()


leftLangLabel.font = UIFontMetrics.default.scaledFont(for: leftLangLabel.font)
}

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