import Foundation
let pattern = #".+?\/([^\/]+?\).+)$"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = #"""
url(../img/repeat-elements/tpl-action-section_bg-1200.png) no-repeat 50%/1200px;
url(../img/pages/home/what-is_bg-1400.png) no-repeat 100% 50%/500px;
url(../img/blog/action/action_1-1400.png) no-repeat 100% 50%/500px;
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #"ВАЛЕНОК$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