import Foundation
let pattern = ##"""
^ # begin of string
(?:(?!(?:\1|\2|\3)).)*? # ungreedy anything that is not captured by group 1,2,or 3
( # 1th capturing group
(?:\brain\b|\bsunlight\b|\bbark) # Alternation group (answers) \b word-boundaries as needed
)
(?:(?!(?:\1|\2|\3)).)*? # ungreedy anything that is not captured by group 1,2,or 3
( # 3th capturing group
(?:(?!(?:\1|\3))(?:\brain\b|\bsunlight\b|\bbark)) # Answers not captured in group 1 or 3
)
(?:(?!(?:\1|\2|\3)).)*? # ungreedy anything that is not captured by group 1,2,or 3
( # 4th capturing group
(?:(?!(?:\2|\3))(?:\brain\b|\bsunlight\b|\bbark)) # Answers not captured by group 2 or 3
)
(?:(?!(?:\1|\2|\3)).)* # anything that is not captured by group 1,2,or 3
$ # end of string
"""##
let regex = try! NSRegularExpression(pattern: pattern, options: [.anchorsMatchLines, .caseInsensitive, .allowCommentsAndWhitespace])
let testString = #"""
rain. bright sunlight. a dog's bark.
rain. bright rain. a dog's bark.
Barksunlight rain
bark sun rain
bar sunlight sunlight
Rain rain rain
sunlight rain bark
Barking dog, sunlight, rainforest
Barking elephant, green Sunlight, purple rain and other non-sense
"""#
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