index indexes and ranges of String

Hi,

I think this is important enough and useful for we to be in the core standard library

extension String {

    func index(of string: String, options: String.CompareOptions = .literal) -> String.Index? {
        return range(of: string, options: options)?.lowerBound
    }

    func indexes(of string: String, options: String.CompareOptions = .literal) -> [String.Index] {
        var result: [String.Index] =
        var start = startIndex
        while let range = range(of: string, options: options, range: start..<endIndex) {
            result.append(range.lowerBound)
            start = range.upperBound
        }
        return result
    }

    func ranges(of string: String, options: String.CompareOptions = .literal) -> [Range<String.Index>] {
        var result: [Range<String.Index>] =
        var start = startIndex
        while let range = range(of: string, options: options, range: start..<endIndex) {
            result.append(range)
            start = range.upperBound
        }
        return result
    }

}

Source is not mine, I’ve found here: Index of a substring in a string with Swift - Stack Overflow

Carlos García