<div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif">​I hope this will show something clearer to you. As you can see, y is defined as OptionalInt?, which is Int??.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">​<span style="font-family:Menlo;font-size:11px;color:rgb(187,44,162)">typealias</span><span style="font-family:Menlo;font-size:11px"> OptionInt = </span><span style="font-family:Menlo;font-size:11px;color:rgb(112,61,170)">Int</span><span style="font-family:Menlo;font-size:11px">?</span></div>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo;min-height:13px"><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo"><span style="color:rgb(187,44,162)">func</span> someThrowingFunction() <span style="color:rgb(187,44,162)">throws</span> -&gt; <span style="color:rgb(79,129,135)">OptionInt</span> {</p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(79,129,135)"><span style="color:rgb(0,0,0)">    </span><span style="color:rgb(187,44,162)">return</span><span style="color:rgb(0,0,0)"> </span>OptionInt<span style="color:rgb(0,0,0)">()</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo">}</p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo;min-height:13px"><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(79,129,135)"><span style="color:rgb(187,44,162)">let</span><span style="color:rgb(0,0,0)"> y: </span>OptionInt?</p><div class="gmail_default" style="font-family:georgia,serif;display:inline">​​</div><p></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo"><span style="color:rgb(187,44,162)">do</span> {</p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(49,89,93)"><span style="color:rgb(0,0,0)">    </span><span style="color:rgb(79,129,135)">y</span><span style="color:rgb(0,0,0)"> = </span><span style="color:rgb(187,44,162)">try</span><span style="color:rgb(0,0,0)"> </span>someThrowingFunction<span style="color:rgb(0,0,0)">()</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(187,44,162)"><span style="color:rgb(0,0,0)">} </span>catch<span style="color:rgb(0,0,0)"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:Menlo">    <span style="color:rgb(79,129,135)">y</span> = <span style="color:rgb(187,44,162)">nil</span></p>