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Core-View-Recycling.html
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<title>NimbusKit: View Recyling</title>
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<div id="projectname">NimbusKit
 <span id="projectnumber">1.2.1 - <a href="http://github.com/jverkoey/nimbus">Fork Nimbus on Github</a> - <a href="http://wiki.nimbuskit.info/">Visit the Nimbus Wiki</a></span>
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<div id="projectbrief">The iOS framework that grows only as fast as its documentation</div>
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<div class="title">View Recyling<div class="ingroups"><a class="el" href="NimbusCore.html">Nimbus Core</a></div></div> </div>
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="nested-classes"></a>
Classes</h2></td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="NIViewRecycler.html">NIViewRecycler</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">An object for efficiently reusing views by recycling and dequeuing them from a pool of views. <a href="NIViewRecycler.html#details">More...</a><br/></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">protocol  </td><td class="memItemRight" valign="bottom"><a class="el" href="NIRecyclableView-Protocol.html"><NIRecyclableView></a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">The <a class="el" href="NIRecyclableView.html" title="A simple implementation of the NIRecyclableView protocol as a UIView. ">NIRecyclableView</a> protocol defines a set of optional methods that a view may implement to handle being added to a <a class="el" href="NIViewRecycler.html" title="An object for efficiently reusing views by recycling and dequeuing them from a pool of views...">NIViewRecycler</a>. <a href="NIRecyclableView-Protocol.html#details">More...</a><br/></td></tr>
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<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="NIRecyclableView.html">NIRecyclableView</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">A simple implementation of the <a class="el" href="NIRecyclableView.html" title="A simple implementation of the NIRecyclableView protocol as a UIView. ">NIRecyclableView</a> protocol as a <a class="el" href="classUIView-Protocol.html">UIView</a>. <a href="NIRecyclableView.html#details">More...</a><br/></td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Overview</h2>
<p>For recycling views in scroll views. </p>
<p>View recycling is an important aspect of iOS memory management and performance when building scroll views. UITableView uses view recycling via the table cell dequeue mechanism. <a class="el" href="NIViewRecycler.html" title="An object for efficiently reusing views by recycling and dequeuing them from a pool of views...">NIViewRecycler</a> implements this recycling functionality, allowing you to implement recycling mechanisms in your own views and controllers.</p>
<h2>Example Use</h2>
<p>Imagine building a UITableView. We'll assume that a viewRecycler object exists in the view.</p>
<p>Views are usually recycled once they are no longer on screen, so within a did scroll event we might have code like the following:</p>
<div class="fragment"><div class="line"><span class="keywordflow">for</span> (UIView<NIRecyclableView>* view in visibleViews) {</div>
<div class="line"> <span class="keywordflow">if</span> (![<span class="keyword">self</span> isVisible:view]) {</div>
<div class="line"> [viewRecycler recycleView:view];</div>
<div class="line"> [view removeFromSuperview];</div>
<div class="line"> }</div>
<div class="line">}</div>
</div><!-- fragment --><p>This will take the views that are no longer visible and add them to the recycler. At a later point in that same didScroll code we will check if there are any new views that are visible. This is when we try to dequeue a recycled view from the recycler.</p>
<div class="fragment"><div class="line">UIView<NIRecyclableView>* view = [viewRecycler dequeueReusableViewWithIdentifier:reuseIdentifier];</div>
<div class="line"><span class="keywordflow">if</span> (nil == view) {</div>
<div class="line"> <span class="comment">// Allocate a new view that conforms to the NIRecyclableView protocol.</span></div>
<div class="line"> view = [[[...]] autorelease];</div>
<div class="line">}</div>
<div class="line">[<span class="keyword">self</span> addSubview:view];</div>
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