import Foundation
let pattern = #"(?m)^(\d{10}):\s+(.+)"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = #"""
1652855102: New connection from xx.xx.xx.xx on port xxxx.
1652855102: Socket error on client <unknown>, disconnecting.
1652855102: Received PUBLISH from 16838547124974742985 (d0, q1, r0, m235, 's/uc/mpd/16838547124974742985', ... (30 bytes))
1652855102: Sending PUBACK to 16838547124974742985 (m235, rc0)
1652855102: Sending PUBLISH to mqtt_7811e829.e2e5e8 (d0, q1, r0, m42277, 's/uc/mpd/16838547124974742985', ... (30 bytes))
1652855102: Sending PUBLISH to dad3d73-013c-4274-a782-cdd6f2ebbc77 (d0, q0, r0, m0, 's/uc/mpd/16838547124974742985', ... (30 bytes))
1652855102: Received PUBACK from mqtt_7811e829.e2e5e8 (Mid: 42277, RC:0)
1652855103: Received DISCONNECT from 16838547082470259932
1652855103: Client 16838547082470259932 disconnected.
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #"$1|$2"#
let result = regex.stringByReplacingMatches(in: testString, range: stringRange, withTemplate: substitutionString)
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