objective-c - NSLinguisticTagger 语言是 "und"

Question

我正在尝试找出字符串的语言。如果我从变量传递它，它会将语言识别为“und”，但如果我将它传递为

 [tagger setString:[NSString stringWithFormat:@"Example 2 Three people have attached a rope around your belly and pull it with the indicated forces. The sketch isn’t true to scale and shows the situation froth above. a) Detennine with a drawing, in what direction you are pulled (assuming that you don’t put up any resistance) Choose a scale of l00N 2 Ion . b) What is the influence of the lengths of the ropes?"]];

它能正确识别语言。两种情况下的文本相同

//Recognize Language for Output
{
    NSArray *tagschemes = [NSArray arrayWithObjects:NSLinguisticTagSchemeLanguage, nil];
    NSLinguisticTagger *tagger = [[NSLinguisticTagger alloc] initWithTagSchemes:tagschemes options:0];
    [tagger setString:[NSString stringWithFormat:@"%@", text]];

    NSString *language = [tagger tagAtIndex:0 scheme:NSLinguisticTagSchemeLanguage tokenRange:NULL sentenceRange:NULL];

    output = [NSString stringWithFormat:@"The language is %@\rand the following words were found:\r\r%@", language, output];

}

“und”是什么语言，为什么它不能正确地将语言识别为 en？

Answer 1

来自 the docs对于 NSOrthography:

如果无法确定特定语言，则使用标签 und。