'String' does not conform to protocol 'CollectionType' Error in Swift 2.0

如下是报错需要修改的源码：

//        if count(currentPassword) < 6 || count(newPassword) < 6 || count(confirmPassword) < 6  {

//            var failAlertView = UIAlertView(title: Localized.ACCOUNT_HINT_PASSWORD , message: nil, delegate: self, cancelButtonTitle: Localized.DIALOG_BUTTON_OK)

//            failAlertView.show()

//            return

//        }

修改如下：

     func setPassword(currentPassword: String, newPassword: String, confirmPassword: String) {

         //may

         if currentPassword.characters.count <  || newPassword.characters.count <  || confirmPassword.characters.count <  {

             let failAlertView = UIAlertView(title: Localized.ACCOUNT_HINT_PASSWORD , message: nil, delegate: self, cancelButtonTitle: Localized.DIALOG_BUTTON_OK)

             failAlertView.show()

             return

         }