import Foundation
let pattern = #"^(?:(?:[\s\w]*(?:({(?:[\s\w]*%\(\w*\)[\s\w]*)+(?:{(?:[\s\w]*%\(\w*\)[\s\w]*)+})*})+)[\s\w]*)+)$"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = ##"""
# Your valid example
abc {st1 %(ph1) st11} int {st2 %(ph2) st22}{st3 %(ph3) st33 {st31 %(ph4) st332}} cd
# Your valid Legenda
OptionalStaticText{OptionalStaticText %(Placeholder) OptionalStaticText {OptionalSubSection} OptionalStaticText} OptionalStaticText
# Your invalid example
abc {st1 %(ph1) st11} int {st2 %(ph2) st22}{st3 %(ph3) st33 {st31 %(ph4) st332}} c-d
# Without pre / post optional static text and some optional text inside section
{%(Placeholder) OptionalStaticText {OptionalSubSection}}
# With only a placeholder in the section
OptionalStaticText{%(Placeholder)} OptionalStaticText
# The valid version
abc {st1 %(ph1) st11} int {st2 %(ph2) st22}{st3 %(ph3) st33 {st31 %(ph4) st332}} cd
"""##
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let matches = regex.matches(in: testString, range: stringRange)
var result: [[String]] = []
for match in matches {
var groups: [String] = []
for rangeIndex in 1 ..< match.numberOfRanges {
let nsRange = match.range(at: rangeIndex)
guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue }
let string = (testString as NSString).substring(with: nsRange)
groups.append(string)
}
if !groups.isEmpty {
result.append(groups)
}
}
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