<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Aug 18, 2016, at 12:54 PM, Adel Zhang <<a href="mailto:adelzhang@qq.com" class="">adelzhang@qq.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span 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;" class="">Any other situation when implicit type casting works? It would be better if there is a reference or link.</span><br class=""></div></blockquote><br class=""></div><div>From the Swift Programming Language book, the section “Optional Type”:</div><div><br class=""></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div>The type Optional<Wrapped> is an enumeration with two cases, none and some(Wrapped), which are used to represent values that may or may not be present. <b class="">Any type can be explicitly declared to be (or implicitly converted to) an optional type</b>. If you don’t provide an initial value when you declare an optional variable or property, its value automatically defaults to nil.</div></blockquote><div><br class=""></div><div>—Jens</div></body></html>