Challenge Accepted #2 - Signed API Request

GenerateRequest.swft

let inputDictionary = [
    "author_name": "Robert Jordan",
    "book_title": "Knife of Dreams",
    "series": "The Wheel of Time, Book 11",
    "publisher": "Tor Fantasy",
    "published_date": "November 28, 2006"
]

let sortedKeys = inputDictionary.keys.array.sorted(<)
var queryTerms = Array<String>()
for key in sortedKeys {
    let encodedKey = key.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet())!
    let encodedValue = inputDictionary[key]!.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet())!
    queryTerms += ["\(encodedKey)=\(encodedValue)"]
}
let now = NSDate()
queryTerms += ["timestamp=\(Int(now.timeIntervalSince1970 * 1000.0))"]
let hashInputString = "&".join(queryTerms) + "1234MySuperSecretKey4321"

// NOTE: This next line makes use of the CryptoSwift library (https://github.com/krzyzanowskim/CryptoSwift/)
if let hash = hashInputString.sha1() {
    queryTerms += ["signature=\(hash)"]
    let finalQueryString = "&".join(queryTerms)
    println(finalQueryString)
} else {
    println("ERROR: Unable to create SHA-1 hash.")
}