---
layout: "default"
title: "ForwardIndexType"
description: "Swift documentation for 'ForwardIndexType': Represents a discrete value in a series, where a value&#39;s
successor, if any, is reachable by applying the value&#39;s
successor() method."
keywords: "ForwardIndexType,protocol,swift,documentation,==,advancedBy,advancedBy,distanceTo,successor,Distance"
root: "/v2.1"
---

<div class="intro-declaration"><code class="language-swift">protocol ForwardIndexType</code></div>

<div class="discussion comment">