gistfile1.txt

func convertCurrency(#localAmount:Double, localCurrency:String, foreignCurrency: String)-> Double {
    
    let baseURL = NSURL(string: "http://www.freecurrencyconverterapi.com/api/v2/")
    let query = String(localCurrency)+"_"+String(foreignCurrency)
    let forecastURL = NSURL(string: "convert?q="+query, relativeToURL: baseURL)
    
    
    //use a session object to manage.//like the sun
    let sharedSession = NSURLSession.sharedSession()
    var convertedAmount:Double = 0.0
    
    let downloadTask:NSURLSessionDownloadTask = sharedSession.downloadTaskWithURL(forecastURL, completionHandler: { (location:NSURL!, response: NSURLResponse!, error: NSError!) -> Void in
        
        if error == nil {
            let dataObject = NSData(contentsOfURL: location)
            let conversionDictionary:NSDictionary = NSJSONSerialization.JSONObjectWithData(dataObject, options: nil, error: nil) as NSDictionary
            if let results = conversionDictionary["results"] as? NSDictionary{
                if let queryResults = results[query] as? NSDictionary{
                    if let exchangeRate = queryResults["val"] as? Double{
                        convertedAmount = (localAmount * exchangeRate) as Double
                        print(convertedAmount)
                        
                    }
                }
            }
            
        }
    })
    
    downloadTask.resume()
    
    return convertedAmount
    
    
}

convertCurrency(localAmount: 10, "JPY", "HKD")