import Foundation
let pattern = #"(?i)^(test)(?:=[0-9]{0,})?$"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = #"""
Test
Test=
Test=45
Test45
Match text: (?i)^test(?:=[0-9]{0,})?$
Match has number:	.*?=[0-9]{1,}$
Extract number: .*=([0-9]{1,})$
"""#
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