ios 如何在 Objective C (NSRegularExpression) 中编写正则表达式？

How to write regular expressions in Objective C (NSRegularExpression)?

提问by budidino

I have this regex working when I test it in PHP but it doesn't work in Objective C:

当我在 PHP 中测试它时，我有这个正则表达式工作，但它在目标 C 中不起作用：

(?:www\.)?((?!-)[a-zA-Z0-9-]{2,63}(?<!-))\.?((?:[a-zA-Z0-9]{2,})?(?:\.[a-zA-Z0-9]{2,})?)

I tried escaping the escape characters but that doesn't help either. Should I escape any other character?

我尝试转义转义字符，但这也无济于事。我应该转义任何其他角色吗？

This is my code in Objective C:

这是我在目标 C 中的代码：

NSMutableString *searchedString = [NSMutableString stringWithString:@"domain-name.tld.tld2"];
NSError* error = nil;

NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern:@"(?:www\.)?((?!-)[a-zA-Z0-9-]{2,63}(?<!-))\.?((?:[a-zA-Z0-9]{2,})?(?:\.[a-zA-Z0-9]{2,})?)" options:0 error:&error];
NSArray* matches = [regex matchesInString:searchedString options:0 range:NSMakeRange(0, [searchedString length])];
for ( NSTextCheckingResult* match in matches )
{
    NSString* matchText = [searchedString substringWithRange:[match range]];
    NSLog(@"match: %@", matchText);
}

-- UPDATE --

- 更新 -

This regex returns (in PHP) the array with values "domain-name" and "tld.tld2" but in Objective C i get only one value: "domain-name.tld.tld2"

这个正则表达式返回（在 PHP 中）具有值“domain-name”和“tld.tld2”的数组，但在 Objective C 中我只得到一个值：“domain-name.tld.tld2”

-- UPDATE 2 --

-- 更新 2 --

This regex extracts 'domain name' and 'TLD' from the string:

此正则表达式从字符串中提取“域名”和“顶级域名”：

• domain.com = (domain, com)
• domain.co.uk = (domain, co.uk)
• -test-domain.co.u = (test-domain, co)
• -test-domain.co.uk- = (test-domain, co.uk)
• -test-domain.co.u-k = (test-domain, co)
• -test-domain.co-m = (test-domain)
• -test-domain-.co.uk = (test-domain)

• domain.com =（域，com）
• domain.co.uk =（域，co.uk）
• -test-domain.co.u = (test-domain, co)
• -test-domain.co.uk- = (test-domain, co.uk)
• -test-domain.co.uk = (test-domain, co)
• -test-domain.co-m =（测试域）
• -test-domain-.co.uk = (test-domain)

it takes the valid domain name (not starting or ending with '-' and between 2 and 63 characters long), and up to two parts of a TLD if the parts are valid (at least two characters long containing only letters and numbers)

它需要有效的域名（不以“-”开头或结尾，长度在 2 到 63 个字符之间），如果部分有效，则最多包含 TLD 的两个部分（至少两个字符长仅包含字母和数字）

Hope this explanation helps.

希望这个解释有帮助。

回答by zaph

A NSTextCheckingResulthas multiple items obtained by indexing into it.

ANSTextCheckingResult具有通过索引获得的多个项目。

[match rangeAtIndex:0];is the full match.
[match rangeAtIndex:1];(if it exists) is the first capture group match.
etc.

[match rangeAtIndex:0];是完全匹配。
[match rangeAtIndex:1];（如果存在）是第一个捕获组匹配。
等等。

You can use something like this:

你可以使用这样的东西：

NSString *searchedString = @"domain-name.tld.tld2";
NSRange   searchedRange = NSMakeRange(0, [searchedString length]);
NSString *pattern = @"(?:www\.)?((?!-)[a-zA-Z0-9-]{2,63}(?<!-))\.?((?:[a-zA-Z0-9]{2,})?(?:\.[a-zA-Z0-9]{2,})?)";
NSError  *error = nil;

NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern: pattern options:0 error:&error];
NSArray* matches = [regex matchesInString:searchedString options:0 range: searchedRange];
for (NSTextCheckingResult* match in matches) {
    NSString* matchText = [searchedString substringWithRange:[match range]];
    NSLog(@"match: %@", matchText);
    NSRange group1 = [match rangeAtIndex:1];
    NSRange group2 = [match rangeAtIndex:2];
    NSLog(@"group1: %@", [searchedString substringWithRange:group1]);
    NSLog(@"group2: %@", [searchedString substringWithRange:group2]);
}

NSLog output:

NSLog 输出：

match: domain-name.tld.tld2
domain-name
tld.tld2

匹配： domain-name.tld.tld2
域名
tld.tld2

Do test that the match ranges are valid.

测试匹配范围是否有效。

More simply in this case:

在这种情况下更简单：

NSString *searchedString = @"domain-name.tld.tld2";
NSRange   searchedRange = NSMakeRange(0, [searchedString length]);
NSString *pattern = @"(?:www\.)?((?!-)[a-zA-Z0-9-]{2,63}(?<!-))\.?((?:[a-zA-Z0-9]{2,})?(?:\.[a-zA-Z0-9]{2,})?)";
NSError  *error = nil;

NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:&error];
NSTextCheckingResult *match = [regex firstMatchInString:searchedString options:0 range: searchedRange];
NSLog(@"group1: %@", [searchedString substringWithRange:[match rangeAtIndex:1]]);
NSLog(@"group2: %@", [searchedString substringWithRange:[match rangeAtIndex:2]]);

Swift 3.0:

斯威夫特 3.0：

let searchedString = "domain-name.tld.tld2"
let nsSearchedString = searchedString as NSString
let searchedRange = NSMakeRange(0, searchedString.characters.count)
let pattern = "(?:www\.)?((?!-)[a-zA-Z0-9-]{2,63}(?<!-))\.?((?:[a-zA-Z0-9]{2,})?(?:\.[a-zA-Z0-9]{2,})?)"

do {
    let regex = try NSRegularExpression(pattern:pattern, options: [])
    let matches = regex.matches(in:searchedString, options:[], range:searchedRange)
    for match in matches {
        let matchText = nsSearchedString.substring(with:match.range);
        print("match: \(matchText)");

        let group1 : NSRange = match.rangeAt(1)
        let matchText1 = nsSearchedString.substring(with: group1)
        print("matchText1: \(matchText1)")

        let group2 = match.rangeAt(2)
        let matchText2 = nsSearchedString.substring(with: group2)
        print("matchText2: \(matchText2)")
    }
} catch let error as NSError {
    print(error.localizedDescription)
}

print output:

打印输出：

match: domain-name.tld.tld2
matchText1: domain-name
matchText2: tld.tld2

匹配：域名.tld.tld2
matchText1：域名
matchText2：tld.tld2

More simply in this case:

在这种情况下更简单：

do {
    let regex = try NSRegularExpression(pattern:pattern, options: [])
    let match = regex.firstMatch(in:searchedString, options:[], range:searchedRange)

    let matchText1 = nsSearchedString.substring(with: match!.rangeAt(1))
    print("matchText1: \(matchText1)")

    let matchText2 = nsSearchedString.substring(with: match!.rangeAt(2))
    print("matchText2: \(matchText2)")

} catch let error as NSError {
    print(error.localizedDescription)
}

print output:

打印输出：

matchText1: domain-name
matchText2: tld.tld2

matchText1：域名
matchText2：tld.tld2

回答by hwaxxer

According to Apple's documentation, these characters must be quoted (using \) to be treated as literals:

根据Apple 的文档，这些字符必须被引用（使用 \）才能被视为文字：

* ? + [ ( ) { } ^ $ | \ . /

It would also help if you could explain what you are trying to achieve. Do you have any test fixtures?

如果您能解释您要实现的目标，这也会有所帮助。你有任何测试夹具吗？