throws如何用

例如这种系统的方法。后面带着throws的如何实现它；

 public func createDirectoryAtPath(path: String, withIntermediateDirectories createIntermediates: Bool, attributes: [String : AnyObject]?) throws

//实现它

        do {

            try FM.createDirectoryAtPath(cachePath, withIntermediateDirectories: true, attributes: nil)

            } catch let error as NSError{

                print("存储路径错误-->\(error)")

            }