Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

r"
"
gsx

Test String

Code Generator

Generated Code

import Foundation let pattern = ##""" (?P<content>.*?) # Content up to next tag (?P<markup> # Entire tag <!\[CDATA\[(?P<cdata>.+?)]]>| # <![CDATA[ ... ]]> <!--(?P<comment>.+?)-->| # <!-- Comment --> </\s*(?P<close_tag>\w+)\s*>| # </tag> <(?P<tag>\w+) # <tag ... (?P<attributes> (?P<attribute>\s+ # <snip>: Use this part to get the attributes out of 'attributes' group. (?P<attribute_name>\w+) (?:\s*=\s* (?P<attribute_value> [\w:/.\-]+| # Unquoted (?=(?P<_v> # Quoted (?P<_q>['\"]).*?(?<!\\)(?P=_q))) (?P=_v) ))? # </snip> )* )\s* (?P<is_self_closing>/?) # Self-closing indicator >) # End of tag """## let regex = try! NSRegularExpression(pattern: pattern, options: [.allowCommentsAndWhitespace, .dotMatchesLineSeparators]) let testString = #""" In this case, $url will indeed contain http://example.com/whatever.jpg. But what happens when you start getting HTML like this: <img src='http://example.com/whatever.jpg'> or <img src=http://example.com/whatever.jpg> or <img border=0 src="http://example.com/whatever.jpg"> or <img border src="http://example.com/whatever.jpg"> or <img src="http://example.com/whatever.jpg"> or you start getting false positives from <!-- // commented out <img src="http://example.com/outdated.png"> --> <script><![CDATA[ This is <b>not</b> parsed ]]></script> <asd ASD=asd> <!-- // commented out <img src="http://example.com/outdated.png"> --> No quotes: <iframe src=test.html target=xyz></ iframe > Self-closing tag: <a href=test.html target=xyz/> Self closing tag with a space before closure: <a href=test.html target=xyz /> Double quotes: <a href="test.html" target="xyz"> Single quotes: <a href='test.html' target='xyz'> Escaping double quotes: <a href="test.html?val=1" title="\"No rules exist\" Andre Breton's quote"> Escaping single quotes (also with spaces between equals signs): <a href = "test.html?val=1" title = 'Charlie\'s Angels'> Tag without closure (ignored): <a href = "test.html?val=1" title='Charlie\'s Angels' Tag without opening (ignored): a href = "test.html?val=1" title="Charlie\"s Angels"> """# let stringRange = NSRange(location: 0, length: testString.utf16.count) let matches = regex.matches(in: testString, range: stringRange) var result: [[String]] = [] for match in matches { var groups: [String] = [] for rangeIndex in 1 ..< match.numberOfRanges { let nsRange = match.range(at: rangeIndex) guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue } let string = (testString as NSString).substring(with: nsRange) groups.append(string) } if !groups.isEmpty { result.append(groups) } } print(result)

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression