String+Extensions.swift

extension String {
 
    // MARK: - Substring
 
    private func index(from: Int) -> Index {
        self.index(startIndex, offsetBy: from)
    }

    func substring(from: Int) -> String {
        let fromIndex = index(from: from)
        return String(self[fromIndex...])
    }

    func substring(to: Int) -> String {
        let toIndex = index(from: to)
        return String(self[..<toIndex])
    }

    func substring(with r: Range<Int>) -> String {
        let startIndex = index(from: r.lowerBound)
        let endIndex = index(from: r.upperBound)
        return String(self[startIndex..<endIndex])
    }
 
     // MARK: - Bytes

    func toBytesArray() -> [UInt8] {

        var bytesArray = [UInt8](repeating: 0x00, count: count)

        for (i, ch) in utf8.enumerated() {

            bytesArray[i] = ch
        }

        return bytesArray
    }

    // MARK: - Trimming
 
    func trim() -> String {
        trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
    }
}