import Foundation
let pattern = ##"""
(?:\s|^) # Start of string or word boundary
( # Capture Group
(?:  # Non-Capture Group for X.
(?:    # Nested NCG for 0..255
(?:\d){1,2}|  # Allow any single digit or any pair of digits or
(?:1\d{2})|   # 3 Digits starting with 1 or
(?:2[0-4]\d)| # 3 Digists starting with 20..24 or
(?:25[0-5])   # 250..255
)      # this should allow X=0..255 in the NCG
\.     # Must be followed by a literal .
){3} # X. Must repeat exactly 3 times
(?: # NCG for final 0..255
(?:\d{1,2})|  # Allow any single digit or any pair of digits or
(?:1\d{2})|   # 3 Digits starting with 1 or
(?:2[0-4]\d)| # 3 digits starting 20..24 or
(?:25[0-5])  # 250.255
)   # End of final 0.255
) # End of capture group
(?:\s|$) # Must be followed by EOS or wspace
"""##
let regex = try! NSRegularExpression(pattern: pattern, options: .allowCommentsAndWhitespace)
let testString = #"123.123.123.145 is an IP4 so is 1.2.3.4 and 1.22.33.44 but 256.1.2.3 isn't 254.1.2.3 is but 260.1.1.1 isn't nor 2.5.256.1 and 1.2.3.4:222 IP6 1.2.3.4.5.6"#
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