121 lines
4.9 KiB
HTML
121 lines
4.9 KiB
HTML
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<head>
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<title>Using the GNU Compiler Collection (GCC): Using fast enumeration</title>
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Fast-enumeration.html#Fast-enumeration" rel="up" title="Fast enumeration">
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<link href="c99_002dlike-fast-enumeration-syntax.html#c99_002dlike-fast-enumeration-syntax" rel="next" title="c99-like fast enumeration syntax">
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<a name="Using-fast-enumeration"></a>
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<p>
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Next: <a href="c99_002dlike-fast-enumeration-syntax.html#c99_002dlike-fast-enumeration-syntax" accesskey="n" rel="next">c99-like fast enumeration syntax</a>, Up: <a href="Fast-enumeration.html#Fast-enumeration" accesskey="u" rel="up">Fast enumeration</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Using-Fast-Enumeration"></a>
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<h4 class="subsection">8.9.1 Using Fast Enumeration</h4>
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<p>GNU Objective-C provides support for the fast enumeration syntax:
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</p>
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<div class="smallexample">
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<pre class="smallexample"> id array = …;
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id object;
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for (object in array)
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{
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/* Do something with 'object' */
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}
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</pre></div>
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<p><code>array</code> needs to be an Objective-C object (usually a collection
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object, for example an array, a dictionary or a set) which implements
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the “Fast Enumeration Protocol” (see below). If you are using a
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Foundation library such as GNUstep Base or Apple Cocoa Foundation, all
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collection objects in the library implement this protocol and can be
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used in this way.
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</p>
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<p>The code above would iterate over all objects in <code>array</code>. For
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each of them, it assigns it to <code>object</code>, then executes the
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<code>Do something with 'object'</code> statements.
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</p>
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<p>Here is a fully worked-out example using a Foundation library (which
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provides the implementation of <code>NSArray</code>, <code>NSString</code> and
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<code>NSLog</code>):
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</p>
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<div class="smallexample">
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<pre class="smallexample"> NSArray *array = [NSArray arrayWithObjects: @"1", @"2", @"3", nil];
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NSString *object;
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for (object in array)
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NSLog (@"Iterating over %@", object);
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</pre></div>
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