How parse byte size strings into actual number?

Do you mean you want to extract value from the String ?

Are you sure the format is always ddddddcccc (digits followed by chars) ? Could there be a decimal point ?

I see at least 2 options:

• extract leading characters as long as they are Int

• write a regex (cleaner solution). Some help here: https://stackoverflow.com/questions/30342744/swift-how-to-get-integer-from-string-and-convert-it-into-integer

It seems I can use the builtin Scanner class:

public extension String {
    func parseByteSize() -> UInt64? {
        var n: UInt64 = 0
        let scanner = Scanner(string: self)

        if scanner.scanUnsignedLongLong(&n) {
            if !scanner.isAtEnd {
                let suffix = self[self.index(self.startIndex, offsetBy: scanner.scanLocation)...]
                switch suffix.uppercased() {
                case "KB":
                    n *= 1024
                case "MB":
                    n *= 1024 * 1024
                case "GB":
                    n *= 1024 * 1024 * 1024
                case "TB":
                    n *= 1024  * 1024 * 1024 * 1024
                default:
                    return nil
                }
            }
            return n
        }
        return nil
    }
}