import Foundation
let pattern = #"\{\{ *(ab|cd|ef|gh) *\}\} *\{\{ *(ab|cd|ef|gh) *\}\} *(\{\{ *(ab|cd|ef|gh) *\}\})* *(\{\{ *(ab|cd|ef|gh) *\}\})* *(\{\{ *(ab|cd|ef|gh) *\}\})* *(\{\{ *(ab|cd|ef|gh) *\}\})*"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = #"""
{{ab}}{{ab}}{{ab}}{{ab}}{{ab}}{{ab}}
{{ab}} {{ab}} {{ab}} {{ab}} {{ab}} {{ab}}
machintruc {{ab}} {{cd}}
{{ab}} {{cd}} {{ef}} [https://truc.org truc]
{{ab}}{{ cd }}{{ ef }} {{ gh }} {{ gh }}{{lien web|url=tr.uc}}
{{mr}} Trucmuche
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #"{{mul|$1|$2|$4|$6|$8|$10}} "#
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