<html><head></head><body>This is correct. None of your types does conform to your protocol because you never conformance explicitly. <div><br></div><div>The extenstion you wrote is just a conditional extension which says if the Self type conforms to AreaProtocol and the associated typed Element is a CGPoint then add the area method to it. Nothing more, nothing less.</div><div><br></div><div>Now you may think that you have to rewrite that extension to `extension Sequence : AreaProtocol where Element == CGPoint`, but that won't work because retroactively conforming protocols to other protocols is not supported yet. Nor are conditional conformances included yet, but they will in Swift 4.1 or 5.</div><div><br></div><div>You have one option left.</div><div>protocol MySequence : Sequence, AreaProtocol where Element == CGPoint {}</div><div><br></div><div>extension Array : MySequence {}</div><div><br></div><div>Then also conform other sequences you need to support that functionality.</div><div><br></div><div>Double check if the code compiles, I wrote it on my iPhone, but you get the idea now.</div><div> <br><div class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">-- <br>Adrian Zubarev<br>Sent with Airmail</div></div> <p class="gmail_quote" style="color:#000;">Am 25. November 2017 um 07:40:25, Antonino Ficarra via swift-users (<a href="mailto:swift-users@swift.org">swift-users@swift.org</a>) schrieb:</p> <blockquote type="cite" class="gmail_quote"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div></div><div>
<title></title>
<div style="font-size: 14px;" class="">In this code example:</div>
<div style="font-size: 14px;" class=""><br class=""></div>
<div class="">
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">import</span>
Foundation</div>
<div style="margin: 0px; font-stretch: normal; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">protocol</span>
AreaProtocol {</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class=""><span style="color: rgb(186, 45, 162);" class="">func</span> area() -> <span style="color: rgb(112, 61, 170);" class="">CGFloat</span></div>
<p style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 16px;" class=""><br class="webkit-block-placeholder"></p>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class="">// implemented in protocol extension</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">func</span> volume(
height:<span style="color: #703daa" class="">CGFloat</span> ) ->
<span style="color: #703daa" class="">CGFloat</span></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class="">// ....</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class="">}</div>
<div style="margin: 0px; font-stretch: normal; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(79, 129, 135); background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">extension</span>
AreaProtocol <span style="color: #000000" class="">{</span></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">func</span> volume(
height:<span style="color: #703daa" class="">CGFloat</span> ) ->
<span style="color: #703daa" class="">CGFloat</span> {</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">return</span> height
* <span style="color: #31595d" class="">area</span>()</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class="">}</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class="">// ....</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class="">// ....</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class="">}</div>
<div style="margin: 0px; font-stretch: normal; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div>
<div style="margin: 0px; font-stretch: normal; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class="">// conform CGPoint sequences to AreaProtocol</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(186, 45, 162); background-color: rgb(255, 255, 255);" class="">extension <span style="color: #703daa" class="">Sequence</span></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(79, 129, 135); background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">where</span> Self
<span style="color: #000000" class="">:</span>
AreaProtocol<span style="color: #000000" class="">,</span>
<span style="color: #703daa" class="">Element</span> <span style="color: #000000" class="">==</span> <span style="color: #703daa" class="">CGPoint</span></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class="">{</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">func</span>
area() -> <span style="color: #703daa" class="">CGFloat </span>{</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">return</span>
<span style="color: #272ad8" class="">0.0</span> // ... poligon
area</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class="">}</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class="">}</div>
<div style="margin: 0px; font-stretch: normal; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">let</span> p0 =
<span style="color: #703daa" class="">CGPoint</span>(x:
<span style="color: #272ad8" class="">0.0</span>, y: <span style="color: #272ad8" class="">0.0</span>)</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">let</span> p1 =
<span style="color: #703daa" class="">CGPoint</span>(x:
<span style="color: #272ad8" class="">2.0</span>, y: <span style="color: #272ad8" class="">0.0</span>)</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">let</span> p2 =
<span style="color: #703daa" class="">CGPoint</span>(x:
<span style="color: #272ad8" class="">2.0</span>, y: <span style="color: #272ad8" class="">2.0</span>)</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">let</span> p3 =
<span style="color: #703daa" class="">CGPoint</span>(x:
<span style="color: #272ad8" class="">0.0</span>, y: <span style="color: #272ad8" class="">2.0</span>)</div>
<div style="margin: 0px; font-stretch: normal; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">let</span> poligon =
[<span style="color: #4f8187" class="">p0</span>,<span style="color: #4f8187" class="">p1</span>,<span style="color: #4f8187" class="">p2</span>,<span style="color: #4f8187" class="">p3</span>]</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">let</span>
<span style="color: #000000" class="">a =</span> <span style="color: #4f8187" class="">poligon</span><span style="color: #000000" class="">.</span><span style="text-decoration: underline ; color: #000000" class="">a</span><span style="color: #000000" class="">rea()</span>// !
Type '[CGPoint]' does not conform to protocol 'AreaProtocol'</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class=""><span style="color: #ba2da2" class="">let</span>
<span style="color: #000000" class="">v =</span> <span style="text-decoration: underline ; color: #4f8187" class="">p</span><span style="color: #4f8187" class="">oligon</span><span style="color: #000000" class="">.volume(
height:</span><span style="color: #272ad8" class="">10.0</span>
<span style="color: #000000" class="">)</span>// ! Value of type
'[CGPoint]' has no member 'volume'</div>
<div style="margin: 0px; font-stretch: normal; line-height: normal; background-color: rgb(255, 255, 255); min-height: 14px;" class=""><br class=""></div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class=""><br class=""></div>
</div>
<div style="margin: 0px; font-stretch: normal; font-size: 14px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0); background-color: rgb(255, 255, 255);" class="">
<div style="color: rgb(0, 0, 0); font-family: Helvetica;" class="">
An array of CGPoint is a CGPoint sequence? Why the array don't gets
automatic conformance to AreaProtocol?</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica;" class="">
How can conform an array of CGPoint to AreaProtocol?</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica;" class="">
<br class=""></div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica;" class="">
Sorry for my bad english,</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica;" class="">
Antonino</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px;" class=""><br class=""></div>
</div>
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