Using a regular expression to check for a possible rule structure

regex.swift

let pattern = "(greater|more|)(.+)(than|)(.+)"
let regex = try! NSRegularExpression(pattern: pattern, options: .CaseInsensitive)

let text = "more blue triangles than red circles"
let matches = regex.matchesInString(text, options: [], range: NSRange(location: 0, length: text.characters.count))

if let match = matches.first {
    let seperator1 = (text as NSString).substringWithRange(match.rangeAtIndex(1))
    let fragment1 = (text as NSString).substringWithRange(match.rangeAtIndex(2))
    let seperator2 = (text as NSString).substringWithRange(match.rangeAtIndex(3))
    let fragment2 = (text as NSString).substringWithRange(match.rangeAtIndex(4))
}