import Foundation
let pattern = #"""
(?sx)
(?|
０(?=.*(0))
|１(?=.*(1))
|２(?=.*(2))
|３(?=.*(3))
|４(?=.*(4))
|５(?=.*(5))
|６(?=.*(6))
|７(?=.*(7))
|８(?=.*(8))
|９(?=.*(9))
)
"""#
let regex = try! NSRegularExpression(pattern: pattern, options: [.allowCommentsAndWhitespace, .dotMatchesLineSeparators])
let testString = #"""
０ zero
１ ichi
２ ni
３ san
４ shi
５ go
６ roku
７ shichi
８ hachi
９ kyuu
0123456789
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #"\1"#
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