在原来又长又臭的名字基础上简单扩展下，方便使用

extension String {
    /*
     *去掉首尾空格
     */
    var removeHeadAndTailSpace:String {
        let whitespace = NSCharacterSet.whitespaceCharacterSet()
        return self.stringByTrimmingCharactersInSet(whitespace)
    }
    /*
    *去掉首尾空格 包括后面的换行 \n
    */
    var removeHeadAndTailSpacePro:String {
        let whitespace = NSCharacterSet.whitespaceAndNewlineCharacterSet()
        return self.stringByTrimmingCharactersInSet(whitespace)
    }
    /*
     *去掉所有空格
     */
    var removeAllSapce:String {
        return self.stringByReplacingOccurrencesOfString(" ", withString: "", options: .LiteralSearch, range: nil)
    }
    /*
     *去掉首尾空格 后 指定开头空格数
     */
    func beginSpaceNum(num: Int) -> String {
        var beginSpace = ""
        for _ in 0..<num {
            beginSpace += " "
        }
       return beginSpace + self.removeHeadAndTailSpacePro
    }
}