正则表达式模式匹配并在Swift中替换 [英] Regex pattern match and replace in Swift

问题描述

我有如下字符串:

这是％1 $ s，产品％2 $ s 这是％2 $ s，产品为％2 $ s

我想用{0}替换％1 $ s ，并用{1}替换％2 $ s ，依此类推.

I want to replace %1$s by {0}, and %2$s by {1} and so on..

我试图做到:

let range = NSRange(location: 0, length: myString.count)
var regex = try! NSRegularExpression(pattern: "%[1-9]\\$s", options: [])
var newStr = regex.stringByReplacingMatches(in: myString, options: [], range: range, withTemplate: "XXXX")

任何人都可以帮助我！

推荐答案

您的模式是错误的，因为您的开头是 [a-z] ，所以您什么都没检测到.

Your pattern is wrong, you have at the start [a-z], so you aren't detecting anything.

此外，更喜欢使用NSStuff的utf16计数(因为使用NSString，它是UTF16)

Also, prefers utf16 count with NSStuff (because with NSString, it's UTF16)

let myString = "Hi this is %1$s, product %2$s Hi this is %2$s, product %2$s"

let range = NSRange(location: 0, length: myString.utf16.count)
var regex = try! NSRegularExpression(pattern: "%(\\d+)\\$s", options: [])
var newStr = regex.stringByReplacingMatches(in: myString, options: [], range: range, withTemplate: "{$1}")
print(newStr)

输出:

$>Hi this is {1}, product {2} Hi this is {2}, product {2}

关于％(\ d +)\ $ s 的一些解释(然后对Swift字符串重做 \ ).
％:检测到％"
\ d + :检测号码(包括之前没有的12个号码)
(\ d +):检测编号，但在捕获组中
\ $ :检测"$"(需要转义，因为它是正则表达式中的特殊字符)
s :检测到"s"

Some explanation on %(\d+)\$s (and then redo a \ for Swift strings).
% : Detect "%"
\d+: Detect number (including 12 which weren't your case before)
(\d+): Detect number, but in a capture group
\$: Detect "$" (need an escape because it's a special char in regex)
s: Detect "s"

因此，有两组:整体(对应于整个正则表达式匹配项)和数字.第一个是$ 0，第二个是$ 1，这就是为什么我在模板中使用 {$ 1} .

So there are two groups: The whole (corresponding to the whole regex match), and the numbers. The first one would be $0, and the second one $1, that's why I used {$1} in the template.

注意:我使用 https://regex101.com 来检查模式.

NB: I used https://regex101.com to check the pattern.

使用增量，您将无法使用模板.您必须枚举所有匹配项，进行操作并替换.

With increment, you can't do it with the template. You have to enumerate all the matches, do the operation and replace.

var myString = "Hi this is %1$s, product %2$s Hi this is %2$s, product %2$s"
let range = NSRange(location: 0, length: myString.utf16.count)
var regex = try! NSRegularExpression(pattern: "%(\\d+)\\$s", options: [])
let matches = regex.matches(in: myString, options: [] , range: range)
matches.reversed().forEach({ aMatch in
    let fullNSRange = aMatch.range
    guard let fullRange = Range(fullNSRange, in: myString) else { return }
    let subNSRange = aMatch.range(at: 1)
    guard let subRange = Range(subNSRange, in: myString) else { return }
    let subString = myString[subRange]
    guard let subInt = Int(subString) else { return }
    let replacement = "{" + String(subInt + 1) + "}"
    myString.replaceSubrange(fullRange, with: replacement)
})

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