Swift替换子串正则表达式 [英] Swift replace substring regex

问题描述

我正在尝试使用正则表达式替换字符串中所有出现的英国汽车注册。

I am attempting to use regular expression to replace all occurrences of UK car registrations within a string.

以下swift代码适用于字符串匹配时正则表达式如下所示。

The following swift code works perfectly for a when the string matches the regex exactly as below.

var myString = "DD11 AAA"
var stringlength = countElements(myString) 
var ierror: NSError?
var regex:NSRegularExpression = NSRegularExpression(pattern: "^([A-HK-PRSVWY][A-HJ-PR-Y])\\s?([0][2-9]|[1-9][0-9])\\s?[A-HJ-PR-Z]{3}$", options: NSRegularExpressionOptions.CaseInsensitive, error: &ierror)!
var modString = regex.stringByReplacingMatchesInString(myString, options: nil, range: NSMakeRange(0, stringlength), withTemplate: "XX")
print(modString)

结果是 XX

但是，以下不起作用且字符串未修改

However, the following does not work and the string is not modifed

var myString = "my car reg 1 - DD11 AAA  my car reg 2 - AA22 BBB"
var stringlength = countElements(myString) 
var ierror: NSError?
var regex:NSRegularExpression = NSRegularExpression(pattern: "^([A-HK-PRSVWY][A-HJ-PR-Y])\\s?([0][2-9]|[1-9][0-9])\\s?[A-HJ-PR-Z]{3}$", options: NSRegularExpressionOptions.CaseInsensitive, error: &ierror)!
var modString = regex.stringByReplacingMatchesInString(myString, options: nil, range: NSMakeRange(0, stringlength), withTemplate: "XX")
print(modString)

结果是我的汽车注册1 - DD11 AAA我的汽车注册2 - AA22 BBB

任何人都可以给我任何指示吗？

Can anyone give me any pointers?

推荐答案

你需要删除 ^ 和 $ 锚点。

^ 表示开始字符串， $ 表示字符串结尾（或线，取决于选项）。这就是你的第一个例子工作的原因：在第一个测试字符串中，字符串的开头后面跟着你的模式，并以它结束。

The ^ means start of string and $ means end of string (or line, depending on the options). That's why your first example works: in the first test string, the start of the string is really followed by your pattern and ends with it.

在第二个测试字符串中，模式位于字符串的中间，因此 ^ ... 无法应用。如果您只是删除 ^ ， $ 将适用于第二次出现的注册号，输出将是我的车注册1 - DD11 AAA我的车注册2 - XX 。

In the second test string, the pattern is found in the middle of the string, thus the ^... can't apply. If you would just remove the ^, the $ would apply on the second occurrence of the registration number and the output would be my car reg 1 - DD11 AAA my car reg 2 - XX.

let myString = "my car reg 1 - DD11 AAA  my car reg 2 - AA22 BBB"
let regex = try! NSRegularExpression(pattern: "([A-HK-PRSVWY][A-HJ-PR-Y])\\s?([0][2-9]|[1-9][0-9])\\s?[A-HJ-PR-Z]{3}", options: NSRegularExpressionOptions.CaseInsensitive)
let range = NSMakeRange(0, myString.characters.count)
let modString = regex.stringByReplacingMatchesInString(myString, options: [], range: range, withTemplate: "XX")
print(modString)
// Output: "my car reg 1 - XX  my car reg 2 - XX"

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