在 iOS 上使用 ML Kit 辨識文字語言

您可以使用 ML Kit 來識別文本字符串的語言。您可以獲得字符串最可能的語言或獲得字符串所有可能語言的置信度分數。

ML Kit 可以識別 103 種不同語言的本機腳本中的文本。此外，可以識別阿拉伯語、保加利亞語、中文、希臘語、印地語、日語和俄語的羅馬化文本。

在你開始之前

  1. 如果您尚未將 Firebase 添加到您的應用，請按照入門指南中的步驟進行操作。
  2. 在您的 Podfile 中包含 ML Kit 庫： 
    pod 'Firebase/MLNaturalLanguage', '6.25.0'
pod 'Firebase/MLNLLanguageID', '6.25.0'
    安裝或更新項目的 Pod 後，請務必使用其.xcworkspace打開您的 Xcode 項目。
  3. 在您的應用中，導入 Firebase：

    迅速

    import Firebase

    Objective-C

    @import Firebase;

識別字符串的語言

要識別字符串的語言，請獲取LanguageIdentification的實例，然後將字符串傳遞給identifyLanguage(for:)方法。

例如：

迅速

let languageId = NaturalLanguage.naturalLanguage().languageIdentification()

languageId.identifyLanguage(for: text) { (languageCode, error) in
  if let error = error {
    print("Failed with error: \(error)")
    return
  }
  if let languageCode = languageCode, languageCode != "und" {
    print("Identified Language: \(languageCode)")
  } else {
    print("No language was identified")
  }
}

Objective-C

FIRNaturalLanguage *naturalLanguage = [FIRNaturalLanguage naturalLanguage];
FIRLanguageIdentification *languageId = [naturalLanguage languageIdentification];

[languageId identifyLanguageForText:text
                         completion:^(NSString * _Nullable languageCode,
                                      NSError * _Nullable error) {
                           if (error != nil) {
                             NSLog(@"Failed with error: %@", error.localizedDescription);
                             return;
                           }
                           if (languageCode != nil
                               && ![languageCode isEqualToString:@"und"] ) {
                             NSLog(@"Identified Language: %@", languageCode);
                           } else {
                             NSLog(@"No language was identified");
                           }
                         }];

如果調用成功，則將BCP-47 語言代碼傳遞給完成處理程序，指示文本的語言。請參閱支持語言的完整列表。如果無法可靠地檢測到任何語言，則通過代碼und （未確定）。

默認情況下，ML Kit 僅在識別出置信度值至少為 0.5 的語言時才返回非und值。您可以通過將LanguageIdentificationOptions對像傳遞給languageIdentification(options:)來更改此閾值：

迅速

let options = LanguageIdentificationOptions(confidenceThreshold: 0.4)
let languageId = NaturalLanguage.naturalLanguage().languageIdentification(options: options)

Objective-C

FIRNaturalLanguage *naturalLanguage = [FIRNaturalLanguage naturalLanguage];
FIRLanguageIdentificationOptions *options =
    [[FIRLanguageIdentificationOptions alloc] initWithConfidenceThreshold:0.4];
FIRLanguageIdentification *languageId =
    [naturalLanguage languageIdentificationWithOptions:options];

獲取字符串的可能語言

要獲取字符串最可能語言的置信度值，請獲取LanguageIdentification的實例，然後將字符串傳遞給identifyPossibleLanguages(for:)方法。

例如：

迅速

let languageId = NaturalLanguage.naturalLanguage().languageIdentification()

languageId.identifyPossibleLanguages(for: text) { (identifiedLanguages, error) in
  if let error = error {
    print("Failed with error: \(error)")
    return
  }
  guard let identifiedLanguages = identifiedLanguages,
    !identifiedLanguages.isEmpty,
    identifiedLanguages[0].languageCode != "und"
  else {
    print("No language was identified")
    return
  }

  print("Identified Languages:\n" +
    identifiedLanguages.map {
      String(format: "(%@, %.2f)", $0.languageCode, $0.confidence)
      }.joined(separator: "\n"))
}

Objective-C

FIRNaturalLanguage *naturalLanguage = [FIRNaturalLanguage naturalLanguage];
FIRLanguageIdentification *languageId = [naturalLanguage languageIdentification];

[languageId identifyPossibleLanguagesForText:text
                                  completion:^(NSArray<FIRIdentifiedLanguage *> * _Nonnull identifiedLanguages,
                                               NSError * _Nullable error) {
  if (error != nil) {
    NSLog(@"Failed with error: %@", error.localizedDescription);
    return;
  }
  if (identifiedLanguages.count == 1
      && [identifiedLanguages[0].languageCode isEqualToString:@"und"] ) {
    NSLog(@"No language was identified");
    return;
  }
  NSMutableString *outputText = [NSMutableString stringWithFormat:@"Identified Languages:"];
  for (FIRIdentifiedLanguage *language in identifiedLanguages) {
    [outputText appendFormat:@"\n(%@, %.2f)", language.languageCode, language.confidence];
  }
  NSLog(outputText);
}];

如果調用成功，則將IdentifiedLanguage對象列表傳遞給繼續處理程序。從每個對像中，您可以獲得該語言的 BCP-47 代碼以及該字符串是該語言的置信度。請參閱支持語言的完整列表。請注意，這些值表示整個字符串使用給定語言的置信度； ML Kit 不會在單個字符串中識別多種語言。

默認情況下，ML Kit 僅返回置信度值至少為 0.01 的語言。您可以通過將LanguageIdentificationOptions對像傳遞給languageIdentification(options:)來更改此閾值：

迅速

let options = LanguageIdentificationOptions(confidenceThreshold: 0.4)
let languageId = NaturalLanguage.naturalLanguage().languageIdentification(options: options)

Objective-C

FIRNaturalLanguage *naturalLanguage = [FIRNaturalLanguage naturalLanguage];
FIRLanguageIdentificationOptions *options =
    [[FIRLanguageIdentificationOptions alloc] initWithConfidenceThreshold:0.4];
FIRLanguageIdentification *languageId =
    [naturalLanguage languageIdentificationWithOptions:options];

如果沒有語言符合此閾值，則列表將包含一項，其值為und 。