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POScripting Bridge and filtering SBElementArrays using NSPredicate and FourCharCodes
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  1. POScripting Bridge and filtering SBElementArrays using NSPredicate and FourCharCodes
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    copied!<p>I'm experimenting with Scripting Bridge for the the first time, but have run into an issue with filtering a <code>SBElementArray</code> according to a NSPredicate containing a FourCharCode enum constant as a criterion.</p> <p>I wrote a trivial program to identify the "library" source in a user's iTunes library, by using <code>-filteredArrayUsingPredicate:</code> to filter the <code>SBElementArray</code> of all iTunes sources. I was expecting to get back an <code>SBElementArray</code> that, when evaluated, would produce an array of one element, namely the library source. Instead, when I call <code>-get</code> on the returned <code>SBElementArray</code>, I get back an empty array.</p> <p>Perplexingly, if change the order and instead call <code>-get</code> on the <code>SBElementArray</code> of all sources to get a concrete <code>NSArray</code>, and call <code>-filteredArrayUsingPredicate:</code> on this array with the same predicate as before, I do get the desired result. I don't believe this is supposed to be necessary however, and I've had success filtering a <code>SBElementArray</code> using other NSPredicates (e.g. <code>@"name=='Library'"</code> works fine).</p> <p>The code snippet is below. <code>iTunesESrcLibrary</code> is a FourCharCode constant defined in the header file generated by Scripting Bridge. (<code>iTunesESrcLibrary = 'kLib'</code>). I'm running 10.6.5.</p> <pre><code>iTunesApplication* iTunes = [[SBApplication alloc] initWithBundleIdentifier:@"com.apple.iTunes"]; NSPredicate* libraryPredicate = [NSPredicate predicateWithFormat:@"kind == %u", iTunesESrcLibrary]; SBElementArray* allSources_Attempt1 = [iTunes sources]; SBElementArray* allLibrarySources_Attempt1 = (SBElementArray*)[allSources_Attempt1 filteredArrayUsingPredicate:libraryPredicate]; NSLog(@"Attempt 1: %@", allLibrarySources_Attempt1); NSLog(@"Attempt 1 (evaluated): %@", [allLibrarySources_Attempt1 get]); NSArray* allSources_Attempt2 = [[iTunes sources] get]; NSArray* allLibrarySources_Attempt2 = [allSources_Attempt2 filteredArrayUsingPredicate:libraryPredicate]; NSLog(@"Attempt 2: %@", allLibrarySources_Attempt2); </code></pre> <p>The output I get is the following:</p> <pre><code>Attempt 1: &lt;SBElementArray @0x3091010: ITunesSource whose 'cmpd'{ 'relo':'= ', 'obj1':'obj '{ 'want':'prop', 'from':'exmn'($$), 'form':'prop', 'seld':'pKnd' }, 'obj2':1800169826 } of application "iTunes" (88827)&gt; Attempt 1 (evaluated): ( ) Attempt 2: ( "&lt;ITunesSource @0x3091f10: ITunesSource id 65 of application \"iTunes\" (88827)&gt;" ) </code></pre>
 

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