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| <h4 class="subsection">8.9.1 Using fast enumeration</h4> |
| |
| <p>GNU Objective-C provides support for the fast enumeration syntax: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"> id array = …; |
| id object; |
| |
| for (object in array) |
| { |
| /* Do something with 'object' */ |
| } |
| </pre></div> |
| |
| <p><code>array</code> needs to be an Objective-C object (usually a collection |
| object, for example an array, a dictionary or a set) which implements |
| the “Fast Enumeration Protocol” (see below). If you are using a |
| Foundation library such as GNUstep Base or Apple Cocoa Foundation, all |
| collection objects in the library implement this protocol and can be |
| used in this way. |
| </p> |
| <p>The code above would iterate over all objects in <code>array</code>. For |
| each of them, it assigns it to <code>object</code>, then executes the |
| <code>Do something with 'object'</code> statements. |
| </p> |
| <p>Here is a fully worked-out example using a Foundation library (which |
| provides the implementation of <code>NSArray</code>, <code>NSString</code> and |
| <code>NSLog</code>): |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"> NSArray *array = [NSArray arrayWithObjects: @"1", @"2", @"3", nil]; |
| NSString *object; |
| |
| for (object in array) |
| NSLog (@"Iterating over %@", object); |
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