swift 之 URL编码

func encodeEscapesURL(value:String) -> String {
let str:NSString = value
let originalString = str as CFStringRef
let charactersToBeEscaped = "!*'();:@&=+$,/?%#[]" as CFStringRef  //":/?&=;+!@#$()',*"    //转意符号
//let charactersToLeaveUnescaped = "[]." as CFStringRef  //保留的符号
let result =
CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
originalString,
nil,    //charactersToLeaveUnescaped,
charactersToBeEscaped,
CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding)) as NSString

return result as String
}