---
layout: "default"
title: "ExtensibleCollectionType"
description: "Swift documentation for 'ExtensibleCollectionType': A collection type that can be efficiently appended-to."
keywords: "ExtensibleCollectionType,protocol,swift,documentation,append,extend,generate,reserveCapacity,endIndex,startIndex,Generator,Index,_Element"
root: "/v1.2"
---

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

<div class="discussion comment">
    <p>A collection type