Swift 4 string extension to find all ranges of some substring

Ranges.swift

extension StringProtocol where Index == String.Index {
    func ranges<T: StringProtocol>(of substring: T, options: String.CompareOptions = [], locale: Locale? = nil) -> [Range<Index>] {
        var ranges: [Range<Index>] = []
        while let result = range(of: substring, options: options, range: (ranges.last?.upperBound ?? startIndex)..<endIndex, locale: locale) {
            ranges.append(result)
        }
        return ranges
    }
}

Or also,

let string = "Administrator or worker in office"

let pattern = Regex {
    Anchor.wordBoundary
    "or"
    Anchor.wordBoundary
}.ignoresCase()

for match in string.matches(of: pattern) {
    print(string[match.range])
}