Swift Apple 的自然语言 API 返回意外结果

I'm trying to figure out why Apple's Natural Language API returns unexpected results.

我做错了什么？这是语法问题吗？

我有以下四个字符串，我想提取每个单词的"stem form"

    // text 1 has two "accredited" in a different order
    let text1: String = "accredit accredited accrediting accredited accreditation accredits"
    
    // text 2 has three "accredited" in different order
    let text2: String = "accredit accredits accredited accrediting accredited accredited accreditation"
    
    // text 3 has "accreditation"
    let text3: String = "accreditation"
    
    // text 4 has "accredited"
    let text4: String = "accredited"

问题在于单词accreditation和accredited.

"accreditation"这个词再也没有出现在词干上.和accredited根据单词在字符串中的顺序返回不同的结果，如附图中的文本1和文本2所示.

我已经用了Apple's documentation的密码

以下是SwiftUI的完整代码:

import SwiftUI
import NaturalLanguage

struct ContentView: View {
    
    // text 1 has two "accredited" in a different order
    let text1: String = "accredit accredited accrediting accredited accreditation accredits"
    
    // text 2 has three "accredited" in a different order
    let text2: String = "accredit accredits accredited accrediting accredited accredited accreditation"
    
    // text 3 has "accreditation"
    let text3: String = "accreditation"
    
    // text 4 has "accredited"
    let text4: String = "accredited"
    
    var body: some View {
        ScrollView {
            VStack {
                
                Text("Text 1").bold()
                tagText(text: text1, scheme: .lemma).padding(.bottom)
                
                Text("Text 2").bold()
                tagText(text: text2, scheme: .lemma).padding(.bottom)
                
                Text("Text 3").bold()
                tagText(text: text3, scheme: .lemma).padding(.bottom)
                
                Text("Text 4").bold()
                tagText(text: text4, scheme: .lemma).padding(.bottom)
                
            }
        }
    }
    
    // MARK: - tagText
    func tagText(text: String, scheme: NLTagScheme) -> some View {
        VStack {
            ForEach(partsOfSpeechTagger(for: text, scheme: scheme)) { word in
                Text(word.description)
            }
        }
    }
    
    // MARK: - partsOfSpeechTagger
    func partsOfSpeechTagger(for text: String, scheme: NLTagScheme) -> [NLPTagResult] {
        
        var listOfTaggedWords: [NLPTagResult] = []
        let tagger = NLTagger(tagSchemes: [scheme])
        tagger.string = text
        
        let range = text.startIndex..<text.endIndex
        let options: NLTagger.Options = [.omitPunctuation, .omitWhitespace]
        
        tagger.enumerateTags(in: range, unit: .word, scheme: scheme, options: options) { tag, tokenRange in
            
            if let tag = tag {
                let word: String = String(text[tokenRange])
                let result = NLPTagResult(word: word, tag: tag)
                
                //if !word.localizedCaseInsensitiveContains(tag.rawValue) {
                listOfTaggedWords.append(result)
                //}
            }
            return true
        }
        
        return listOfTaggedWords
    }
    
    // MARK: - NLPTagResult
    struct NLPTagResult: Identifiable, Equatable, Hashable, Comparable {
        var id = UUID()
        var word: String
        var tag: NLTag?
        
        var description: String {
            var newString: String = "\(word)"
            
            if let tag = tag {
                newString += " : \(tag.rawValue)"
            }
            
            return newString
        }
        
        // MARK: - Equatable & Hashable requirements
        static func == (lhs: Self, rhs: Self) -> Bool {
            lhs.id == rhs.id
        }
        
        func hash(into hasher: inout Hasher) {
            hasher.combine(id)
        }
        
        // MARK: - Comparable requirements
        static func <(lhs: NLPTagResult, rhs: NLPTagResult) -> Bool {
            lhs.id.uuidString < rhs.id.uuidString
        }
    }
    
}

// MARK: - Previews
struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

谢谢你的帮助！