A position in a <code>CharacterView</code> instance.
    <code>characterIndex</code> must be an element of
    <code>String(utf8).characters.indices</code>.
  <strong>utf8:</strong> The <code>UTF8View</code> in which to find the new position.</p>

    <h4>Declaration</h4>    
    <code class="language-swift">init(_ characterIndex: Index, within unicodeScalars: String.UnicodeScalarView)</code>

    </div></div>
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