如何encode：

let urlStrEncode = urlStr.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)

或者

let urlStrEncode = urlStr.stringByAddingPercentEncodingWithAllowedCharacters( NSCharacterSet.URLQueryAllowedCharacterSet())

顺道再贴下如何decode：

let urlStrDecode = urlStrEncoded.stringByRemovingPercentEncoding