import Foundation
let pattern = #"\n(?![^<]*<\/pre>)"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = ##"""
<p>Test contennt for regex
with line breaks</p>
<pre>code block
with multi line content
working fine</pre>
<pre class="brush:C#">
test line break before
open paranthesis < is not working fine
line breaks after paranthesis
is accepted
</pre>
"""##
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