# 227-Font Management and Text Scaling

# New system fonts

Rounded: used in Schedule
Serif: used in Book
Monospaced: used in Swift Playground

# New API

extension UIFontDescriptor.SystemDesign {
  static let `default`: UIFontDescriptor.SystemDesign
  static let rounded: UIFontDescriptor.SystemDesign
  static let serif: UIFontDescriptor.SystemDesign
  static let monospaced: UIFontDescriptor.SystemDesign }
  open func withDesign(_ design: UIFontDescriptor.SystemDesign) -> UIFontDescriptor?
}

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# Demo

let descriptor = UIFont.systemFont(ofSize: 17.0, weight: .bold).fontDescriptor
if let roundedDescriptor = descriptor.withDesign(.rounded) {
let roundedBoldFont = UIFont(descriptor: roundedDescriptor, size: 0.0)
  //
}

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# Installing and accessing user fonts

Font Provider—Installing Fonts

Ability to register fonts system wide
Setting app to manage fonts

Entitlements—Fonts

# New API

CoreText/CTFontManager.h

CTFontManagerRegisterFontURLs

CTFontManagerUnregisterFontURLs

CTFontManagerRegisterFontDescriptors

CTFontManagerUnregisterFontDescriptors

CTFontManagerRegisterFontsWithAssetNames

CTFontManagerCopyRegisteredDescriptors

CTFontManagerRequestFonts

Font Consumer—Loading Fonts

# Font selection

新增 UIFontPickerViewController, 在 Mac 上作为 Menu 展示，因为需要展示在按钮上，因此需要使用 UIPopoverPresentationController 来控制

UIPopoverPresentationController 是 UIPresentationController 的子类，用于控制 presentation style = UIModalPresentationStyle.popover 的展示效果

UITextFormattingCoordinator 在 Mac 上展示 Font Panel

Adopt some of the new UIResponderStandardEditActions protocol methods in order to be notified when changes are made through the Font Panel, for example updateTextAttributes method

# Demo

func updateTextAttributes(conversionHandler: UITextAttributesConversionHandler) {
  // Create a new mutable string
  let newString = NSMutableAttributedString(string: attributedString.string)
  // Enumerate attributes to modify
  attributedString.enumerateAttributes(in: NSMakeRange(0, attributedString.length),
  options: []) { (attributeDictionary, range, stop) in
    // Get the updated attributes
    newString.setAttributes(conversionHandler(attributeDictionary), range: range)
  }
}

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# Text scaling

Visual consistency impacts cross-platform user experience

iPad Apps for Mac
Copy and Paste
Document interchange

17 point in iOS

13 point in Mac

# New API

enum NSTextScalingType {
  case iOS       // in iOS
  case standard  // in Mac
}

class UITextView {
  var usesStandardTextScaling: Bool { get set }
}

static let textScaling: NSAttributedString.DocumentAttributeKey 
static let sourceTextScaling: NSAttributedString.DocumentAttributeKey
static let targetTextScaling: NSAttributedString.DocumentReadingOptionKey
static let sourceTextScaling: NSAttributedString.DocumentReadingOptionKey

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