忽略转义的双引号字符 [英] Ignore escaped double quote characters swift

问题描述

我正在尝试使用 NSPredicate 和正则表达式来验证电话号码。唯一的问题是在设置正则表达式时，Swift认为由于反斜杠，我正试图对其进行转义。我该如何解决？

I am trying to validate a phone number using NSPredicate and regex. The only problem is when setting the regex Swift thinks that I am trying to escape part of it due to the backslashes. How can I get around this?

我的代码如下：

let phoneRegEx = "^((\(?0\d{4}\)?\s?\d{3}\s?\d{3})|(\(?0\d{3}\)?\s?\d{3}\s?\d{4})|(\(?0\d{2}\)?\s?\d{4}\s?\d{4}))(\s?\#(\d{4}|\d{3}))?$"

推荐答案

在Swift中，您仍然需要双斜杠转义在字符串文字中定义文字反斜杠：

In Swift, you still need to double-escape the slashes in string literals to define literal backslashes:

let phoneRegEx = "^((\\(?0\\d{4}\\)?\\s?\\d{3}\\s?\\d{3})|(\\(?0\\d{3}\\)?\\s?\\d{3}\\s?\\d{4})|(\\(?0\\d{2}\\)?\\s‌​?\\d{4}\\s?\\d{4}))(\\s?\\#(\\d{4}|\\d{3}))?$"

请参考正则表达式元字符表strings / regexp rel = nofollow noreferrer> ICU正则表达式 页，以查看应如何以这种方式对正则转义符进行转义。

Please refer to the Regular Expression Metacharacters table on the ICU Regular Expressions page to see what regex escapes should be escaped this way.

请介意正则表达式转义符（在上表中）与字符串文字转义符序列之间的区别，您可以在> 字符串文字中的特殊字符 ：

Please mind the difference between the regex escapes (in the above table) and string literal escape sequences that you may check, say, at Special Characters in String Literals:

字符串文字可以包含以下特殊字符：

String literals can include the following special characters:

• 转义的特殊字符 \0 （空字符）， \\ （反斜线）， \t （水平标签）， \n （换行）， \r （回车）， \ （双引号）和 \'（单引号）


• 任意Unicode标量值，写为 \u {n} ，其中 n 是1到8位的十六进制数字（ Unicode 是

• The escaped special characters \0 (null character), \\ (backslash), \t (horizontal tab), \n (line feed), \r (carriage return), \" (double quotation mark) and \' (single quotation mark)
• An arbitrary Unicode scalar value, written as \u{n}, where n is a 1–8 digit hexadecimal number (Unicode is discussed in Unicode below)

因此， \ 是用字符串文字形式表示的 字符串，您不必在正则表达式引擎中转义双引号，因此 \ 字符串文字正则表达式模式足以匹配字符串中的 char。但是， \\\ （表示 \ 文字字符串的字符串文字）也将匹配 字符，尽管您已经知道此正则表达式模式有多冗余。而且， \n （一个LF符号）以与 \\n 相同的方式匹配换行符，就像 \n 是换行符char的文字表示形式， \\n 是ICU正则表达式转义表中定义的正则表达式转义。

So, "\"" is a " string written as a string literal, and you do not have to escape a double quotation mark for the regex engine, so "\"" string literal regex pattern is enough to match a " char in a string. However, "\\\"", a string literal repesenting \" literal string will also match " char, although you can already see how redundant this regex pattern is. Also, "\n" (an LF symbol) matches a newline in the same way as "\\n" does, as "\n" is a literal representation of the newline char and "\\n" is a regex escape defined in the ICU regex escape table.

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