String+RangeBetween.swift

extension String {
    /// Finds and returns the range of the first occurrence of a given string within a given left and right occurencies Strings.
    func rangeBetween(leftStringOccurence: String, rightStringOccurence: String) -> Range<String.Index>? {
        guard let lowerBound = self.range(of: leftStringOccurence)?.upperBound,
              let upperBound = self.range(of: rightStringOccurence)?.lowerBound,
              lowerBound < upperBound else {
            return nil
        }
        return lowerBound..<upperBound
    }
}