Swift 基于内容检测文本方向

我想知道是否可以根据内容动态设置

UITextView

的文本方向

默认行为如下：如果用LTR语言开始一行，该行将是LTR，但如果用RTL语言开始下一行，该行的方向将更改为RTL

我想要的是基于第一个设置整个段落的方向

---

可能吗？

我自己也有这个问题。通过一点搜索，我们为UITextView做了这个扩展，它可以检测第一个字母的语言，如果需要的话，可以使用RTL。 您需要在设置文本后调用该函数，因此您可能希望在UITextViewDelegate text change“方法中调用它

当然，这是混乱和不完美的。但它为我工作。你可以得到的想法

Swift 3：

extension UITextView {
    func detectRightToLeft() {
        if let text = self.text, !text.isEmpty {
            let tagschemes = NSArray(objects: NSLinguisticTagSchemeLanguage)
            let tagger = NSLinguisticTagger(tagSchemes: tagschemes as! [String], options: 0)
            tagger.string = text

            let language = tagger.tag(at: 0, scheme: NSLinguisticTagSchemeLanguage, tokenRange: nil, sentenceRange: nil)
            if language?.range(of: "he") != nil || language?.range(of: "ar") != nil || language?.range(of: "fa") != nil {
                self.text = text.replacingOccurrences(of: "\n", with: "\n")
                self.textAlignment = .right
                self.makeTextWritingDirectionRightToLeft(nil)
            }else{
                self.textAlignment = .left
                self.makeTextWritingDirectionLeftToRight(nil)
            }
        }
    }
}

---

基于Arash R的优秀答案，这里有一个Swift 4.2扩展，它为UITextView中的每个段落分别选择文本方向

它确定每个段落中最后一个字符的语言。这样，如果您有一个RTL语言的编号列表，则该段落将是RTL

从text change方法调用函数，如果在首次加载ViewController时填充UITextView-从ViewDidLoad

extension UITextView {
    func detectRightToLeft() {
        if let text = self.text, !text.isEmpty { // Set text, make sure it is not nil
            let cleanFile = text.replacingOccurrences(of: "\r", with: "\n")
            var newLineIndices:Array<Int> = []
            for (index, char) in cleanFile.enumerated() {
                if char == "\n" {
                    newLineIndices.append(index) // Get location of all newline characters
                }
            }
            newLineIndices.insert(-1, at: 0) // Place position 0 at the beginning of the array
            newLineIndices.append(cleanFile.count) // Add the location after last character

            let tagschemes = NSArray(objects: NSLinguisticTagScheme.language)
            let tagger = NSLinguisticTagger(tagSchemes: tagschemes as! [NSLinguisticTagScheme], options: 0)
            tagger.string = cleanFile

            for i in 0..<newLineIndices.count-1 {
                // Determine direction by the last character of paragraph
                var taggerCounter = newLineIndices[i+1]-1
                var language = tagger.tag(at: taggerCounter, scheme: NSLinguisticTagScheme.language, tokenRange: nil, sentenceRange: nil)
                // Neutral characters should make the tagger look at the character before
                while language == nil && taggerCounter >= 1 {
                    taggerCounter -= 1
                    language = tagger.tag(at: taggerCounter, scheme: NSLinguisticTagScheme.language, tokenRange: nil, sentenceRange: nil)
                }

                if String(describing: language).range(of: "he") != nil || String(describing: language).range(of: "ar") != nil || String(describing: language).range(of: "fa") != nil {
                    self.setBaseWritingDirection(.rightToLeft, for: self.textRange(from: self.position(from: self.beginningOfDocument, offset: newLineIndices[i]+1)!, to: self.position(from: self.beginningOfDocument, offset: newLineIndices[i+1])!)!)
                    print ("Right to Left Paragraph at character \(newLineIndices[i]+1)")

                } else {
                    self.setBaseWritingDirection(.leftToRight, for: self.textRange(from: self.position(from: self.beginningOfDocument, offset: newLineIndices[i]+1)!, to: self.position(from: self.beginningOfDocument, offset: newLineIndices[i+1])!)!)
                    print ("Left to Right Paragraph at character \(newLineIndices[i]+1)")
                }
            }
        }
    }
}

扩展UITextView{ func detectRightToLeft（）{ 如果let text=self.text，！text.isEmpty{//Set text，请确保它不是nil 让cleanFile=text.replacingOccurrences（of:“\r”，with:“\n”） var newlineindex:Array=[] 对于cleanFile.enumerated（）中的（索引，字符）{ 如果char==“\n”{ newlineindex.append（index）//获取所有换行符的位置 } } newlineindex.insert（-1，at:0）//将位置0放置在数组的开头 newlineindex.append（cleanFile.count）//在最后一个字符后添加位置 让tagschemes=NSArray（对象：nsLanguagisticTagScheme.language） 设tagger=NSLinguisticTagger（tagSchemes:tagSchemes as！[NSLinguisticTagScheme]，选项：0） tagger.string=cleanFile 对于0中的i..=1{ taggerCounter-=1 language=tagger.tag（at:taggerCounter，scheme:nslinguisticstagscheme.language，tokenRange:nil，sentenceRange:nil） } 如果字符串（描述：语言）。范围（of:“he”）！=nil |字符串（描述：语言）。范围（of:“ar”）！=nil |字符串（描述：语言）。范围（of:“fa”）！=nil{ self.setBaseWritingDirection（.right-toleft，for:self.textRange（from:self.beginingofdocument，offset:newlineindex[i]+1）！，to:self.position（from:self.beginingofdocument，offset:newlineindex[i+1]）！） 打印（“字符\（换行索引[i]+1]处从右向左的段落”） }否则{ self.setBaseWritingDirection（.leftToRight，for:self.textRange（from:self.beginingofdocument，offset:newlineindex[i]+1）！，to:self.position（from:self.beginingofdocument，offset:newlineindex[i+1]）！） 打印（“字符\（换行索引[i]+1]处从左到右的段落”） } } } } }

---

编辑：以前的版本包含一个选项，可根据段落的第一个字符进行选择。该选项导致崩溃，因此我暂时将其忽略。相反，当前代码包含中性字符的处理。另一个编辑：将taggerCounter最小值更改为1，以防止其变为负值。

Base关于Ron的答案，这里是字符串的一个更一般的扩展

extension String {

    var isRTL: Bool {
        let cleanFile = self.replacingOccurrences(of: "\r", with: "\n")
        var newLineIndices: Array<Int> = []

        for (index, char) in cleanFile.enumerated() {
            if char == "\n" {
                newLineIndices.append(index)
            }
        }

        newLineIndices.insert(-1, at: 0)
        newLineIndices.append(cleanFile.count)

        let tagschemes = NSArray(objects: NSLinguisticTagScheme.language)
        let tagger = NSLinguisticTagger(tagSchemes: tagschemes as! [NSLinguisticTagScheme], options: 0)
        tagger.string = cleanFile

        for i in 0..<newLineIndices.count - 1 {
            let language = tagger.tag(at: newLineIndices[i + 1] - 1, scheme: NSLinguisticTagScheme.language, tokenRange: nil, sentenceRange: nil)

            if String(describing: language).range(of: "he") != nil || String(describing: language).range(of: "ar") != nil || String(describing: language).range(of: "fa") != nil {
                return true
            } else {
                return false
            }
        }

        return false
    }

    var isLTR: Bool {
        let cleanFile = self.replacingOccurrences(of: "\r", with: "\n")
        var newLineIndices: Array<Int> = []

        for (index, char) in cleanFile.enumerated() {
            if char == "\n" {
                newLineIndices.append(index)
            }
        }

        newLineIndices.insert(-1, at: 0)
        newLineIndices.append(cleanFile.count)

        let tagschemes = NSArray(objects: NSLinguisticTagScheme.language)
        let tagger = NSLinguisticTagger(tagSchemes: tagschemes as! [NSLinguisticTagScheme], options: 0)
        tagger.string = cleanFile

        for i in 0..<newLineIndices.count - 1 {
            let language = tagger.tag(at: newLineIndices[i + 1] - 1, scheme: NSLinguisticTagScheme.language, tokenRange: nil, sentenceRange: nil)

            if String(describing: language).range(of: "he") != nil || String(describing: language).range(of: "ar") != nil || String(describing: language).range(of: "fa") != nil {
                return false
            } else {
                return true
            }
        }

        return false
    }

}

扩展字符串{
var isRTL:Bool{
让cleanFile=self.replacingOccurrences（of:“\r”，with:“\n”）
var newlineindex:Array=[]
对于cleanFile.enumerated（）中的（索引，字符）{
如果char==“\n”{
newlineindex.append（索引）
}
}
newlineindex.insert（-1，at:0）
newlineindex.append（cleanFile.count）
让tagschemes=NSArray（对象：nsLanguagisticTagScheme.language）
设tagger=NSLinguisticTagger（tagSchemes:tagSchemes as！[NSLinguisticTagScheme]，选项：0）
tagger.string=cleanFile
对于0中的i..请看这里：我想它会有帮助。并导致崩溃sometimes@Maysam你能提供一些关于崩溃情况的更多信息吗？此代码在我的应用程序中运行良好。请尝试使用emptytext@Maysam根本不应该发生这种情况。
！text.isEmpty
就是为了这个。
extension String {

    var isRTL: Bool {
        let cleanFile = self.replacingOccurrences(of: "\r", with: "\n")
        var newLineIndices: Array<Int> = []

        for (index, char) in cleanFile.enumerated() {
            if char == "\n" {
                newLineIndices.append(index)
            }
        }

        newLineIndices.insert(-1, at: 0)
        newLineIndices.append(cleanFile.count)

        let tagschemes = NSArray(objects: NSLinguisticTagScheme.language)
        let tagger = NSLinguisticTagger(tagSchemes: tagschemes as! [NSLinguisticTagScheme], options: 0)
        tagger.string = cleanFile

        for i in 0..<newLineIndices.count - 1 {
            let language = tagger.tag(at: newLineIndices[i + 1] - 1, scheme: NSLinguisticTagScheme.language, tokenRange: nil, sentenceRange: nil)

            if String(describing: language).range(of: "he") != nil || String(describing: language).range(of: "ar") != nil || String(describing: language).range(of: "fa") != nil {
                return true
            } else {
                return false
            }
        }

        return false
    }

    var isLTR: Bool {
        let cleanFile = self.replacingOccurrences(of: "\r", with: "\n")
        var newLineIndices: Array<Int> = []

        for (index, char) in cleanFile.enumerated() {
            if char == "\n" {
                newLineIndices.append(index)
            }
        }

        newLineIndices.insert(-1, at: 0)
        newLineIndices.append(cleanFile.count)

        let tagschemes = NSArray(objects: NSLinguisticTagScheme.language)
        let tagger = NSLinguisticTagger(tagSchemes: tagschemes as! [NSLinguisticTagScheme], options: 0)
        tagger.string = cleanFile

        for i in 0..<newLineIndices.count - 1 {
            let language = tagger.tag(at: newLineIndices[i + 1] - 1, scheme: NSLinguisticTagScheme.language, tokenRange: nil, sentenceRange: nil)

            if String(describing: language).range(of: "he") != nil || String(describing: language).range(of: "ar") != nil || String(describing: language).range(of: "fa") != nil {
                return false
            } else {
                return true
            }
        }

        return false
    }

}