<div dir="ltr"><div class="gmail_default"><font face="georgia, serif">Turns out that for `NSObject`, protocol `Equatable` wasn't used. Instead, it used `NSObjectProtocol.isEqual(_ object: Any?)`. Also, override `func isEqual(_ object: Any?) -> Bool` requires to override `var hash: Int { get }` as well.</font></div><div class="gmail_default"><font face="georgia, serif"><br></font></div><div class="gmail_default"><font face="georgia, serif">I think this behavior should be mentioned in Swift docs or manual in `Set` section.</font></div><div class="gmail_default"><font face="georgia, serif"><br></font></div><div class="gmail_default"><font face="georgia, serif">Below code works. </font></div><div class="gmail_default"><font face="georgia, serif"><br></font></div><div class="gmail_default"><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(112,61,170)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Bar:</span><span style="font-variant-ligatures:no-common-ligatures">NSObject</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> value:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">override</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">var</span><span style="font-variant-ligatures:no-common-ligatures"> hashValue: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> == rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">// required by NSObjectProtocol</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">override</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> isEqual(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">_</span><span style="font-variant-ligatures:no-common-ligatures"> object: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">Any</span><span style="font-variant-ligatures:no-common-ligatures">?) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">if</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> rhs = object </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">as</span><span style="font-variant-ligatures:no-common-ligatures">? </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(49,89,93)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(186,45,162)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">return</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">false</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(186,45,162)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">override</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">var</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> hash: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> { </span><span style="font-variant-ligatures:no-common-ligatures">return</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">self</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">hashValue</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">init</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">_</span><span style="font-variant-ligatures:no-common-ligatures"> value:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> = value</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> barSetA:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Set</span><span style="font-variant-ligatures:no-common-ligatures"> = [</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">8</span><span style="font-variant-ligatures:no-common-ligatures">), </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">9</span><span style="font-variant-ligatures:no-common-ligatures">)]</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> barSetB:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Set</span><span style="font-variant-ligatures:no-common-ligatures"> = [</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">9</span><span style="font-variant-ligatures:no-common-ligatures">), </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">10</span><span style="font-variant-ligatures:no-common-ligatures">)]</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> barResultC = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetA</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">intersection</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetB</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures">// {{NSObject, value 9}}</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(112,61,170)">
</p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> barResultD = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetA</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">subtracting</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetB</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures">// {{NSObject, value 8}}</span></p><div><span style="font-variant-ligatures:no-common-ligatures"><br></span></div></div><div class="gmail_default"><font face="georgia, serif">Gladly I find it <a href="http://stackoverflow.com/questions/32726524/swift-2-0-set-not-working-as-expected-when-containing-nsobject-subclass">here</a>. </font></div><div class="gmail_default"><font face="georgia, serif"><br></font></div><div class="gmail_default"><font face="georgia, serif">Zhaoxin</font></div><div class="gmail_default"><br></div><div class="gmail_default"><font face="georgia, serif"><br></font></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Mar 29, 2017 at 3:50 AM, Zhao Xin <span dir="ltr"><<a href="mailto:owenzx@gmail.com" target="_blank">owenzx@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif">Please see the code first.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">import</span><span style="font-variant-ligatures:no-common-ligatures"> Foundation</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(112,61,170)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures">Hashable</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> value:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">var</span><span style="font-variant-ligatures:no-common-ligatures"> hashValue: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> == rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">init</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">_</span><span style="font-variant-ligatures:no-common-ligatures"> value:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> = value</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> fooSetA:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Set</span><span style="font-variant-ligatures:no-common-ligatures"> = [</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">8</span><span style="font-variant-ligatures:no-common-ligatures">), </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">9</span><span style="font-variant-ligatures:no-common-ligatures">)]</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> fooSetB:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Set</span><span style="font-variant-ligatures:no-common-ligatures"> = [</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">9</span><span style="font-variant-ligatures:no-common-ligatures">), </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">10</span><span style="font-variant-ligatures:no-common-ligatures">)]</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> fooResultC = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">fooSetA</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">intersection</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">fooSetB</span><span style="font-variant-ligatures:no-common-ligatures">) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,132,0)">// {{value 9}}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> fooResultD = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">fooSetA</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">subtracting</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">fooSetB</span><span style="font-variant-ligatures:no-common-ligatures">) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,132,0)">// {{value 8}}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(112,61,170)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Bar:</span><span style="font-variant-ligatures:no-common-ligatures">NSObject</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> value:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">override</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">var</span><span style="font-variant-ligatures:no-common-ligatures"> hashValue: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> == rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">init</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">_</span><span style="font-variant-ligatures:no-common-ligatures"> value:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">value</span><span style="font-variant-ligatures:no-common-ligatures"> = value</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> barSetA:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Set</span><span style="font-variant-ligatures:no-common-ligatures"> = [</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">8</span><span style="font-variant-ligatures:no-common-ligatures">), </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">9</span><span style="font-variant-ligatures:no-common-ligatures">)]</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> barSetB:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Set</span><span style="font-variant-ligatures:no-common-ligatures"> = [</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">9</span><span style="font-variant-ligatures:no-common-ligatures">), </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Bar</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(39,42,216)">10</span><span style="font-variant-ligatures:no-common-ligatures">)]</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> barResultC = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetA</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">intersection</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetB</span><span style="font-variant-ligatures:no-common-ligatures">) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,132,0)">// Set([])</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> barResultD = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetA</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">subtracting</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">barSetB</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures">// {{NSObject, value 9}, {NSObject, value 8}}</span></p></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">Behaviors of `func intersection(Set<Set.Element>)<wbr>` and `func subtracting(Set<Set.Element>)` were different between normal Swift class and NSObject subclasses. I had thought they should be the same. It seemed that Set<NSObject> relied on addresses of NSObject instances instead of their hashValues. That made the Set useless.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">Swift version: 3.1 (swiftlang-802.0.48 clang-802.0.48)</div><div class="gmail_default" style="font-family:georgia,serif">Xcode 8.3 (8E162)</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">Zhaoxin</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div></div>
</blockquote></div><br></div>