import Foundation
let pattern = #"From:\s+(?<from>.*?)\s+To:\s+(?<to>.*?)\s+Subject:\s+(?<subject>.*?)(?:\s+References: (?<ref>.*?))?$"#
let regex = try! NSRegularExpression(pattern: pattern, options: [.anchorsMatchLines, .dotMatchesLineSeparators])
let testString = #"""
Text of variable length spread across several lines Serialization-type text separated by colons (eg ABC:DEF:GHI) A date
From: One line of text To: One or more lines Subject: One or more lines References: One or more lines
From: One line of text To: One
or
more
lines Subject: One or more lines References: One or more lines
From: One line of text To: One or more lines Subject: No references.
From: One line of text To: One or more lines Subject: One
or
more
lines
References: One or more lines
Paragraph 1 Title: A paragraph
Paragraph 2 Title: Another paragraph
"""#
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