import Foundation
let pattern = #"\"((http|https)\:\/\/([^\"]+)\.key)\""#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = #"""
<a href="http://site.com/palavra.key"></a>
<a href="https://site.com/palavra.key"></a>
<a href="http://subdominio.site.com/palavra.key"></a>
<a href="https://subdominio.site.com/palavra.chave"></a>
<a href="http://subdominio.site.com/uma_coisa_qualquer.keykey"></a>
<a href="https://subdominio.site.com/outra_coisa_qualquer.key"></a>
<a href="https://subdominio.site.com/outra_coisa_qualquer.keys"></a>
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #""#
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