Compressing/Decompressing UUID to 22 characters via base64

gistfile1.swift

import Foundation

// Compressing and decompressing a UUID to 22 characters via base64.
// Works great as a Swift playground. These articles were helpful:
// http://blog.codinghorror.com/equipping-our-ascii-armor/
// http://69.195.124.60/~jasondoh/2013/08/14/creating-a-short-guid-in-objective-c/

let identifier = NSUUID().uuidString
let base64TailBuffer = "="

func compress(identifier: String) -> String? {
    guard let tempUuid = NSUUID(uuidString: identifier) else { return nil }
    var tempUuidBytes: UInt8 = 0
    tempUuid.getBytes(&tempUuidBytes)
    let data = Data(bytes: &tempUuidBytes, count: 16)
    let base64 = data.base64EncodedString(options: NSData.Base64EncodingOptions())
    return base64.replacingOccurrences(of: base64TailBuffer, with: "")
}

func rehydrate(shortenedIdentifier: String?) -> String? {
    // Expand an identifier out of a CBAdvertisementDataLocalNameKey or service characteristic.
    if shortenedIdentifier == nil {
        return nil
    }
    else {
        // Rehydrate the shortenedIdentifier
        let shortenedIdentifierWithDoubleEquals = shortenedIdentifier! + base64TailBuffer + base64TailBuffer
        let data = Data(base64Encoded: shortenedIdentifierWithDoubleEquals, options: Data.Base64DecodingOptions())
        let tempUuid = NSUUID(uuidBytes: data?.withUnsafeBytes({ UnsafePointer<UInt8>($0) }))
        return tempUuid.uuidString
    }
}

let testCompress = compress(identifier: identifier)
let testRehydrate = rehydrate(shortenedIdentifier: testCompress)