import Foundation
let pattern = #"^(?:(?:(?:(\d+)d\s*)?(\d+)h\s*)?(\d+)m\s*)?(\d+)s$"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = #"""
1d 2h 3m 4s
1h 2m 3s
1m 2s
1s
1d2h3m4s
1h2m3s
1m2s
1s
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #"$1 days $2 hours $3 minutes $4 days"#
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