Ruby text/ Furigana in ios - ios

Question

I am currently trying to display some text in Japanese on a UITextView. Is it possible to display the furigana above the kanji (like below) in a manner similar to the < rt> tag in html, without using a web view?
A lot of text processing is involved, therefore I cannot simply use a web view. In iOS8, CTRubyAnnotationRef was added but there is no documentation (I would welcome any example), and I am also concerned with the lack of compatibility with iOS7. I thought that it would be possible to display the furigana above with the use of an NSAttributedString, but couldn't as of yet.

Answer 1

Update Swift 5.1
This solution is an update of preview answers and let you write Asian sentences with Phonetic Guide, using a pattern in the strings.
Let's start from handling string.
these 4 extension let you to inject in a string the ruby annotation.
the function createRuby() check the string a pattern, that it is: ｜word written in kanji《phonetic guide》.
Examples:
｜紅玉《ルビー》
｜成功《せいこう》するかどうかは、きみの｜努力《どりょく》に｜係《かか》る。
and so on.
the important thing is to follow the pattern.
extension String {
// 文字列の範囲
private var stringRange: NSRange {
return NSMakeRange(0, self.utf16.count)
}
// 特定の正規表現を検索
private func searchRegex(of pattern: String) -> NSTextCheckingResult? {
do {
let patternToSearch = try NSRegularExpression(pattern: pattern)
return patternToSearch.firstMatch(in: self, range: stringRange)
} catch { return nil }
}
// 特定の正規表現を置換
private func replaceRegex(of pattern: String, with templete: String) -> String {
do {
let patternToReplace = try NSRegularExpression(pattern: pattern)
return patternToReplace.stringByReplacingMatches(in: self, range: stringRange, withTemplate: templete)
} catch { return self }
}
// ルビを生成
func createRuby() -> NSMutableAttributedString {
let textWithRuby = self
// ルビ付文字(「｜紅玉《ルビー》」)を特定し文字列を分割
.replaceRegex(of: "(｜.+?《.+?》)", with: ",$1,")
.components(separatedBy: ",")
// ルビ付文字のルビを設定
.map { component -> NSAttributedString in
// ベース文字(漢字など)とルビをそれぞれ取得
guard let pair = component.searchRegex(of: "｜(.+?)《(.+?)》") else {
return NSAttributedString(string: component)
}
let component = component as NSString
let baseText = component.substring(with: pair.range(at: 1))
let rubyText = component.substring(with: pair.range(at: 2))
// ルビの表示に関する設定
let rubyAttribute: [CFString: Any] = [
kCTRubyAnnotationSizeFactorAttributeName: 0.5,
kCTForegroundColorAttributeName: UIColor.darkGray
]
let rubyAnnotation = CTRubyAnnotationCreateWithAttributes(
.auto, .auto, .before, rubyText as CFString, rubyAttribute as CFDictionary
)
return NSAttributedString(string: baseText, attributes: [kCTRubyAnnotationAttributeName as NSAttributedString.Key: rubyAnnotation])
}
// 分割されていた文字列を結合
.reduce(NSMutableAttributedString()) { $0.append($1); return $0 }
return textWithRuby
}
}
Ruby Label: the big problem
As you maybe know, Apple has introduced in iOS 8 the ruby annotation like attribute for the attributedString, and if you did create the the attributed string with ruby annotation and did:
myLabel.attributedText = attributedTextWithRuby
the label did shows perfectly the string without problem.
From iOS 11, Apple unfortunately has removed this feature and, so, if want to show ruby annotation you have override the method draw, to effectively draw the text. To do this, you have to use Core Text to handle the text hand it's lines.
Let's show the code
import UIKit
public enum TextOrientation { //1
case horizontal
case vertical
}
class RubyLabel: UILabel {
public var orientation:TextOrientation = .horizontal //2
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
// ルビを表示
override func draw(_ rect: CGRect) {
//super.draw(rect) //3
// context allows you to manipulate the drawing context (i'm setup to draw or bail out)
guard let context: CGContext = UIGraphicsGetCurrentContext() else {
return
}
guard let string = self.text else { return }
let attributed = NSMutableAttributedString(attributedString: string.createRuby()) //4
let path = CGMutablePath()
switch orientation { //5
case .horizontal:
context.textMatrix = CGAffineTransform.identity;
context.translateBy(x: 0, y: self.bounds.size.height);
context.scaleBy(x: 1.0, y: -1.0);
path.addRect(self.bounds)
attributed.addAttribute(NSAttributedString.Key.verticalGlyphForm, value: false, range: NSMakeRange(0, attributed.length))
case .vertical:
context.rotate(by: .pi / 2)
context.scaleBy(x: 1.0, y: -1.0)
//context.saveGState()
//self.transform = CGAffineTransform(rotationAngle: .pi/2)
path.addRect(CGRect(x: self.bounds.origin.y, y: self.bounds.origin.x, width: self.bounds.height, height: self.bounds.width))
attributed.addAttribute(NSAttributedString.Key.verticalGlyphForm, value: true, range: NSMakeRange(0, attributed.length))
}
attributed.addAttributes([NSAttributedString.Key.font : self.font], range: NSMakeRange(0, attributed.length))
let frameSetter = CTFramesetterCreateWithAttributedString(attributed)
let frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0,attributed.length), path, nil)
// Check need for truncate tail
//6
if (CTFrameGetVisibleStringRange(frame).length as Int) < attributed.length {
// Required truncate
let linesNS: NSArray = CTFrameGetLines(frame)
let linesAO: [AnyObject] = linesNS as [AnyObject]
var lines: [CTLine] = linesAO as! [CTLine]
let boundingBoxOfPath = path.boundingBoxOfPath
let lastCTLine = lines.removeLast() //7
let truncateString:CFAttributedString = CFAttributedStringCreate(nil, "\u{2026}" as CFString, CTFrameGetFrameAttributes(frame))
let truncateToken:CTLine = CTLineCreateWithAttributedString(truncateString)
let lineWidth = CTLineGetTypographicBounds(lastCTLine, nil, nil, nil)
let tokenWidth = CTLineGetTypographicBounds(truncateToken, nil, nil, nil)
let widthTruncationBegins = lineWidth - tokenWidth
if let truncatedLine = CTLineCreateTruncatedLine(lastCTLine, widthTruncationBegins, .end, truncateToken) {
lines.append(truncatedLine)
}
var lineOrigins = Array<CGPoint>(repeating: CGPoint.zero, count: lines.count)
CTFrameGetLineOrigins(frame, CFRange(location: 0, length: lines.count), &lineOrigins)
for (index, line) in lines.enumerated() {
context.textPosition = CGPoint(x: lineOrigins[index].x + boundingBoxOfPath.origin.x, y:lineOrigins[index].y + boundingBoxOfPath.origin.y)
CTLineDraw(line, context)
}
}
else {
// Not required truncate
CTFrameDraw(frame, context)
}
}
//8
override var intrinsicContentSize: CGSize {
let baseSize = super.intrinsicContentSize
return CGSize(width: baseSize.width, height: baseSize.height * 1.0)
}
}
Code explanation:
1- Chinese and japanese text can be written in horizontal and vertical way. This enumeration let you switch in easy way between horizontal and vertical orietantation.
2- public variable with switch orientation text.
3- this method must be commented. the reason is that call it you see two overlapping strings:one without attributes, last your attributed string.
4- here call the method of String class extension in which you create the attributed string with ruby annotation.
5- This switch, rotate if need the context in which draw your text in case you want show vertical text. In fact in this switch you add the attribute NSAttributedString.Key.verticalGlyphForm that in case vertical is true, false otherwise.
6- This 'if' is particular important because, the label, cause we had commented the method 'super.draw()' doesn't know how to manage a long string. without this 'if', the label thinks to have only one line to draw. And so, you still to have a string with '...' like tail. In this 'if' the string is broken in more line and drawing correctly.
7- When you don't give to label some settings, the label knows to have more one line but because it can't calculate what is the showable last piece of string, give error in execution time and the app goes in crash. So be careful. But, don't worry! we talk about the right settings to give it later.
8- this is very important to fit the label to text's size.
How to use the RubyLabel
the use of the label is very simple:
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var rubyLabel: RubyLabel! //1
override func viewDidLoad() {
super.viewDidLoad()
setUpLabel()
}
private func setUpLabel() {
rubyLabel.text = "｜成功《せいこう》するかどうかは、きみの｜努力《どりょく》に｜係《かか》る。｜人々《ひとびと》の｜生死《せいし》に｜係《かか》る。" //2
//3
rubyLabel.textAlignment = .left
rubyLabel.font = .systemFont(ofSize: 20.0)
rubyLabel.orientation = .horizontal
rubyLabel.lineBreakMode = .byCharWrapping
}
}
Code Explanation:
1- connect label to xib if use storyboard or xib file or create label.
2- as I say, the use is very simple: here assign the string with ruby pattern like any other string
3- these setting are the setting to have to set to make work the label. You can set via code or via storyboard/xib
Be careful
if you use storyboard/xib, if you don't put correctly the constraints, the label give you the error at point n° 7.
Result
Works, but not perfect
As you can see by screenshot, this label work well but still has some problem.
1- with vertical text the label still in horizontal shape;
2- if the string contains \n to split the string in more lines, the label shows only the number of lines that the string would have had if was without the '\n' character.
I'm working for fix these problem, but your help is appreciated.

Answer 2

In the end I created a function that gets the kanji's position and create labels every time, above the kanji. It's quite dirty but it's the only way to insure a compatibility with iOS7.
However I have to mention the remarkable examples that you can find on GitHub for the CTRubyAnnotationRef nowadays like : http://dev.classmethod.jp/references/ios8-ctrubyannotationref/
and
https://github.com/shinjukunian/SimpleFurigana
Good luck to all of you !

Answer 3

Here's a focused answer with some comments. This works for UITextView and UILabel on iOS 16.
let rubyAttributes: [CFString : Any] = [
kCTRubyAnnotationSizeFactorAttributeName : 0.5,
kCTRubyAnnotationScaleToFitAttributeName : 0.5,
]
let annotation = CTRubyAnnotationCreateWithAttributes(
.center, // Alignment relative to base text
.auto, // Overhang for adjacent characters
.before, // `before` = above, `after` = below, `inline` = after the base text (for horizontal text)
"Ruby!" as CFString,
rubyAttributes as CFDictionary
)
let stringAttributes = [kCTRubyAnnotationAttributeName as NSAttributedString.Key : annotation]
NSAttributedString(string: "Base Text!", attributes: stringAttributes)
Note, you may want to UITextView.textContainerInset.top to something larger than the default to avoid having the ruby clipped by the scrollview.