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<div class="votecell fl">
<div class="vote">
<span class="vote-up-off" style="cursor: default;">up vote</span>
<span class="vote-count-post">14</span>
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<div class="post-text"><p>Will Swift-based applications work on <a href="http://en.wikipedia.org/wiki/OS_X_Mavericks">OS X 10.9</a> (Mavericks)/iOS 7 and lower?</p>
<p>For example, I have a machine running <a href="http://en.wikipedia.org/wiki/OS_X_Mountain_Lion">OS X 10.8</a> (Mountain Lion), and I am wondering if an application I write in Swift will run on it.</p>
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<a href="/questions/tagged/ios" class="post-tag" title="show questions tagged 'ios'" rel="tag">ios</a> <a href="/questions/tagged/osx" class="post-tag" title="show questions tagged 'osx'" rel="tag">osx</a> <a href="/questions/tagged/swift" class="post-tag" title="show questions tagged 'swift'" rel="tag">swift</a>
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<div class="user-action-time">
asked <span title="2014-06-02 19:25:57Z" class="relativetime">Jun 2 at 19:25</span>
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<div class="gravatar-wrapper-32"><img src="http://i.stack.imgur.com/xDQHx.jpg?s=32&g=1" alt="" width="32" height="32"></div>
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MeIr<br />
<span class="reputation-score" title="reputation score " dir="ltr">1,998</span><span title="5 gold badges"><span class="badge1"></span><span class="badgecount">5</span></span><span title="14 silver badges"><span class="badge2"></span><span class="badgecount">14</span></span><span title="38 bronze badges"><span class="badge3"></span><span class="badgecount">38</span></span>
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<div class="subheader answers-subheader">
<h3>2 Answers</h3>
</div>
<div class="about-a">
<div class="votecell fl">
<div class="vote">
<span class="vote-up-off" style="cursor: default;">up vote</span>
<span class="vote-count-post">4</span>
<span class="vote-down-off" style="cursor: default;">down vote</span>
<span class="vote-accepted-off" style="cursor: default;">accept</span>
</div>
</div>
<div class="postcell fr">
<div class="post-text">
<p>Swift code can be deployed to OS X 10.9 and iOS 7.0. It will usually crash at launch on older OS versions.</p>
</div>
<div class="post-signature fr">
<div class="user-info ">
<div class="user-action-time">
answered <span title="2014-06-03 08:25:37Z" class="relativetime">Jun 3 at 8:25</span>
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Greg Parker<br />
<span class="reputation-score" title="reputation score " dir="ltr">3,861</span><span title="5 silver badges"><span class="badge2"></span><span class="badgecount">5</span></span><span title="15 bronze badges"><span class="badge3"></span><span class="badgecount">15</span></span>
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<div class="about-a">
<div class="votecell fl">
<div class="vote">
<span class="vote-up-off" style="cursor: default;">up vote</span>
<span class="vote-count-post">3</span>
<span class="vote-down-off" style="cursor: default;">down vote</span>
</div>
</div>
<div class="postcell fr">
<div class="post-text">
<p>Apple has announced that Swift apps will be backward compatible with iOS 7 and OS X Mavericks. The WWDC app is written in Swift.</p>
</div>
<div class="post-signature fr">
<div class="user-info ">
<div class="user-action-time">
answered <span title="2014-06-03 00:03:37Z" class="relativetime">Jun 3 at 0:03</span>
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Ben Gottlieb<br />
<span class="reputation-score" title="reputation score 61060" dir="ltr">61.1k</span><span title="10 gold badges"><span class="badge1"></span><span class="badgecount">10</span></span><span title="142 silver badges"><span class="badge2"></span><span class="badgecount">142</span></span><span title="150 bronze badges"><span class="badge3"></span><span class="badgecount">150</span></span>
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<p>All questions are <b>tagged</b> with their subject areas. Each can have up to 5 tags, since a question might be related to several subjects.</p>
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<div class="col-r shadow">
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<div id="question-header">
<h1 class="question-hyperlink">Do Swift-based applications work on OS X 10.9/iOS 7 and lower?</h1>
</div>
<div class="about-q">
<div class="votecell fl">
<div class="vote">
<span class="vote-up-off" style="cursor: default;">up vote</span>
<span class="vote-count-post">14</span>
<span class="vote-down-off" style="cursor: default;">down vote</span>
</div>
</div>
<div class="postcell fr">
<div class="post-text"><p>Will Swift-based applications work on <a href="http://en.wikipedia.org/wiki/OS_X_Mavericks">OS X 10.9</a> (Mavericks)/iOS 7 and lower?</p>
<p>For example, I have a machine running <a href="http://en.wikipedia.org/wiki/OS_X_Mountain_Lion">OS X 10.8</a> (Mountain Lion), and I am wondering if an application I write in Swift will run on it.</p>
</div>
<div class="post-taglist">
<a href="/questions/tagged/ios" class="post-tag" title="show questions tagged 'ios'" rel="tag">ios</a> <a href="/questions/tagged/osx" class="post-tag" title="show questions tagged 'osx'" rel="tag">osx</a> <a href="/questions/tagged/swift" class="post-tag" title="show questions tagged 'swift'" rel="tag">swift</a>
</div>
<div class="post-signature owner fr">
<div class="user-info ">
<div class="user-action-time">
asked <span title="2014-06-02 19:25:57Z" class="relativetime">Jun 2 at 19:25</span>
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MeIr<br />
<span class="reputation-score" title="reputation score " dir="ltr">1,998</span><span title="5 gold badges"><span class="badge1"></span><span class="badgecount">5</span></span><span title="14 silver badges"><span class="badge2"></span><span class="badgecount">14</span></span><span title="38 bronze badges"><span class="badge3"></span><span class="badgecount">38</span></span>
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<div class="about-rep-score col-l">
<p>Your reputation score goes up when others <b>vote up</b> your questions, answers and edits.</p>
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John Doe<br>United States
<br />
<span class="reputation-score" title="reputation score" dir="ltr">245</span>
<span title="3 gold badges"><span class="badge1"></span><span class="badgecount">3</span></span>
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<div class="fr">
<div class="rep-block fl">
<span class="rep-up">+5</span>
question voted up
</div>
<div class="rep-block fl">
<span class="rep-up">+10</span>
answer voted up
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answer is accepted
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<span class="vote-up-off" style="cursor: default;">up vote</span>
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<span class="vote-down-off" style="cursor: default;">down vote</span>
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answered <span title="2014-06-03 08:25:37Z" class="relativetime">Jun 3 at 8:25</span>
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Greg Parker<br />
<span class="reputation-score" title="reputation score " dir="ltr">3,861</span><span title="5 silver badges"><span class="badge2"></span><span class="badgecount">5</span></span><span title="15 bronze badges"><span class="badge3"></span><span class="badgecount">15</span></span>
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<div class="comment-entry border-red">That's as definitive as it gets. Mr. Parker is in the guts of it. - uchuugaka <span title="2014-06-03 09:27:11Z" class="relativetime">Jun 3 at 9:27</span></div>
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</html>Como um browser funciona?
HTML e DOM
Linguagem de marcação, apenas texto.
HTML
DOM
Interface de programação para documentos HTML, XML e SVG.
Provê uma representação estruturada do documento, permitindo acessar esta estrutura, assim como alterar a estrutura, estilo e conteúdo do documento.
Como um browser funciona?
HTML e DOM
<!DOCTYPE html>
<html>
<head>
<title>My title</title>
</head>
<body>
<a href="">My link</a>
<h1>My header</h1>
</body>
</html>HTML
DOM
Como um browser funciona?
CSS e CSSOM
Cascading Style Sheets (CSS) é uma linguagem de estilo usada para descrever a apresentação de um documento escrito em HTML ou em XML (incluindo várias linguagens em XML como SVG ou XHTML).
CSS
CSSOM
Define APIs (incluindo regras de parsing e serialização genéricas) para Seletores, Media Queries, e é claro, o próprio CSS.
Como um browser funciona?
CSS e CSSOM
Seletor seguido de bloco de declarações.
Rule ou Rule set
Como um browser funciona?
Render Tree
Como um browser funciona?
Render Tree
Como um browser funciona?
JavaScript
- Linguagem de scripting
- Orientado a objetos
- Single thread, orientado a eventos
- Seu padrão é o ECMAScript
Como um browser funciona?
JavaScript e DOM
DOM expõe APIs para linguagens de programação (notavelmente JavaScript) acessar e manipular tudo dentro do documento, incluindo sua estrutura, estilo e conteúdo.
Como um browser funciona?
Render blocking
- Nada é renderizado na tela até que todos arquivos CSS estejam carregados.
- Tag <script> (sem os atributo defer/async) bloqueia a construção do DOM até que a mesma seja carregada e executada.
Como um browser funciona?
HTML (DOM)
CSS (CSSOM)
JavaScript
Fontes
- http://css.maxdesign.com.au/selectutorial/rule.htm
- https://developers.google.com/web/fundamentals/performance/critical-rendering-path/render-tree-construction
- https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model
- https://developer.mozilla.org/pt-BR/docs/Web/CSS
- http://dev.w3.org/csswg/cssom/
- http://www.phpied.com/dom-access-optimization/