import Foundation
let pattern = #"(\G(?!^)|<TAG>(?=.*?</TAG>))((?:(?!<TAG>|</TAG>).)*?)abc-"#
let regex = try! NSRegularExpression(pattern: pattern, options: .dotMatchesLineSeparators)
let testString = #"<TAG>test-test-abc-abc-test-abc-test-</TAG>test-abc-test-abc-<TAG>test-abc-test-abc-abc-</TAG>"#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #"$1$2"#
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