<div dir="ltr">Ah, I didn't read the rest of the thread. As Zhao Xin notes, you cannot call super.init(target: self, action: #selector()), and you cannot call super.init() in a subclass init or convenience init, it *has* to be the designated init method init(target:action:). That's too bad, closure-based gesture recognizers would be snazzy and swifty and I'd love to see them as part of UIKit. <div><br></div><div>I could write my own custom implementations of subclassed UIKit.UIGestureRecognizerSubclass(es), but as the screens in question have tap, swipe up, swipe down, and swipe right gesture recognizers, I feel its overkill to write all that to avoid repeating ~10 lines of code.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Jun 4, 2017 at 1:21 AM, Nate Birkholz <span dir="ltr"><<a href="mailto:nbirkholz@gmail.com" target="_blank">nbirkholz@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="auto"><div>I briefly considered something like this but didn't explore it. Elegant.<br><br>Sent from my iPhone, please excuse brevity and errors</div><div><br>On Jun 3, 2017, at 9:38 PM, Geordie Jay <<a href="mailto:geojay@gmail.com" target="_blank">geojay@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div>I am dealing with a variant of this on Android right now. I have just subclassed e.g. UITapGestureRecognizer to perform the 2nd variant above and externally accept a closure as its argument. I'm writing this on my phone so forgive any syntax errors or accidental omissions:<br><br>class TapGestureRecognizer: UITapGestureRecognizer {<br> var onTap: (() -> Void)?<br> init(onTap: (() -> Void)?) {<br> self.onTap = onTap<br> super.init(target: self, action: #selector(internalTapHandler))<br> }<br><br> @objc private func internalTapHandler() {<br> onTap?()<br> }<br>}<br><br>class Baz: Foo {<br> init() {<br> let tapRecognizer = TapGestureRecognizer(onTap: self.bar)<br> }<br>}<br><br><br>Cheers,<br>Geordie<br><div class="gmail_quote"><div dir="ltr">On Sat 3. Jun 2017 at 16:53, Nate Birkholz via swift-users <<a href="mailto:swift-users@swift.org" target="_blank">swift-users@swift.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Thanks, the second had occurred to me, but felt a little too much like in practice it would make the code harder to understand.</div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jun 2, 2017 at 9:58 PM, 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">I found two workarounds.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">1.</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(186,45,162)"><span style="font-variant-ligatures:no-common-ligatures">protocol</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo: </span><span style="font-variant-ligatures:no-common-ligatures">class</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)">func</span><span style="font-variant-ligatures:no-common-ligatures"> bar()</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)">class</span><span style="font-variant-ligatures:no-common-ligatures"> Base:</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></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)">@objc</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"> bar() {</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(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"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></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)">class</span><span style="font-variant-ligatures:no-common-ligatures"> Baz: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Base</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(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">init</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)">super</span><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></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"> tapRecognizer = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">UITapGestureRecognizer</span><span style="font-variant-ligatures:no-common-ligatures">(target: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">, action: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">#selector</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(49,89,93)">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></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></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">2.</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(186,45,162)"><span style="font-variant-ligatures:no-common-ligatures">protocol</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo: </span><span style="font-variant-ligatures:no-common-ligatures">class</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)">func</span><span style="font-variant-ligatures:no-common-ligatures"> bar()</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(186,45,162)"><span style="font-variant-ligatures:no-common-ligatures">extension</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)">Foo</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)">func</span><span style="font-variant-ligatures:no-common-ligatures"> bar() {</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(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"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></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)">class</span><span style="font-variant-ligatures:no-common-ligatures"> Baz: </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></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></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"> tapRecognizer = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">UITapGestureRecognizer</span><span style="font-variant-ligatures:no-common-ligatures">(target: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">, action: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">#selector</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(49,89,93)">delegate</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></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)">@objc</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"> delegate() {</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(49,89,93)">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></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></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">Zhao Xin</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><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Jun 3, 2017 at 10:35 AM, Nate Birkholz via swift-users <span dir="ltr"><<a href="mailto:swift-users@swift.org" target="_blank">swift-users@swift.org</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">protocol Foo: class {<div> func bar()<br><div><div>}</div><div><br></div><div>extension Foo {</div><div> func bar() {</div><div> print("bar")</div><div> }</div><div>}</div><div><br></div><div>class Baz: Foo {</div></div></div><div> init() {</div><div> let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(bar))</div><div> }</div><div><div>}</div><div><br></div><div>the #selector tells me: "Argument of '#selector' refers to instance method 'bar()' that is not exposed to Objective-C" and asks me to add @objc to the method definition. </div><div><br></div><div>Adding @objc to the method tells me: "@objc can only be used with members of classes, @objc protocols, and concrete extensions of classes"</div><div><br></div><div>Adding @objc to the protocol doesn't fix it, just introduces new issues.</div><div><br></div><div>"dynamic" cannot be applied to a protocol, so cannot be used alternatively. </div><div><br></div><div>Is there a way to get around this? If a method is called by a gesture recognizer, is there no way to have a default protocol implementation? I'd like to use default implementations if possible to make my code more DRY.</div><div><br></div><div>Is there a roadmap/plan for swift-native selector dispatch?</div><div><br></div><div>Thanks. I look forward to the inevitable reply revealing the dumb thing I missed. :)</div><span class="HOEnZb"><font color="#888888"><span class="m_-4063239687484628030m_5017937476429152288HOEnZb"><font color="#888888"><span class="m_-4063239687484628030m_5017937476429152288m_7008235823108254220HOEnZb"><font color="#888888"><div><div><br></div>-- <br><div class="m_-4063239687484628030m_5017937476429152288m_7008235823108254220m_8246596659823059447gmail_signature">Nate Birkholz</div>
</div></font></span></font></span></font></span></div></div><span class="HOEnZb"><font color="#888888"><span class="m_-4063239687484628030m_5017937476429152288HOEnZb"><font color="#888888">
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<br></font></span></font></span></blockquote></div><span class="HOEnZb"><font color="#888888"><br></font></span></div><span class="HOEnZb"><font color="#888888">
</font></span></blockquote></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><div><br></div>-- <br><div class="m_-4063239687484628030m_5017937476429152288gmail_signature" data-smartmail="gmail_signature">Nate Birkholz</div>
</font></span></div><span class="HOEnZb"><font color="#888888">
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</font></span></blockquote></div>
</div></blockquote></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature">Nate Birkholz</div>
</div>