<br>Any&nbsp;other&nbsp;situation&nbsp;when&nbsp;implicit&nbsp;type&nbsp;casting&nbsp;works?&nbsp;&nbsp;It&nbsp;would&nbsp;be&nbsp;better&nbsp;if&nbsp;there&nbsp;is&nbsp;a&nbsp;reference&nbsp;or&nbsp;link.<br/><div style="font-size:12px;padding:2px 0;">---Original---</div><div style="font-size:12px;background:#f0f0f0;color:#212121;padding:8px!important;border-radius:4px;line-height:1.5;"><div><b>From:</b> &quot;Jens Alfke&quot;&lt;jens@mooseyard.com&gt;</div><div><b>Date:</b> 2016/8/19 00:27:33</div><div><b>To:</b> &quot;adelzhang&quot;&lt;adelzhang@qq.com&gt;;</div><div><b>Cc:</b> &quot;swift-users&quot;&lt;swift-users@swift.org&gt;;</div><div><b>Subject:</b> Re: [swift-users] Implicitly type conversion ?</div></div><br/><br/><div><blockquote class="" type="cite"><div class="">On Aug 18, 2016, at 12:18 PM, adelzhang via swift-users &lt;<a class="" href="mailto:swift-users@swift.org">swift-users@swift.org</a>&gt; wrote:</div><br/><div class=""><span class="" style="font-family: Alegreya-Regular; font-size: 15px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Why swift don't warn the type mismatch? I am woking on Xcode Version 7.3.1.</span><br/></div></blockquote></div><br/><div class="">It¡¯s an implicit type-cast. Any type `X` can always be implicitly converted to type `X?` (i.e. `Optional&lt;X&gt;`).</div><div class=""><br/></div><div class="">¡ªJens</div>