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POUsing MPMediaQuery to query ios library by rating
 

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    <p>I'm developing an iphone 4 app that filters the local media library by different criteria. I have been able to filter by song name, artist, and genre. Now I need to add a rating filter mechanism. I was thinking in something like "rating >= N stars" (N:0..5)</p> <p>The code I use to filter is:</p> <pre><code>allMedia = [MPMediaQuery songsQuery]; MPMediaPropertyPredicate *mpp1 = [MPMediaPropertyPredicate predicateWithValue:@"2" forProperty:MPMediaItemPropertyRating comparisonType:MPMediaPredicateComparisonEqualTo]; [allMedia addFilterPredicate:mpp1]; </code></pre> <p>But MPMediaPropertyPredicate does not allow to filter by MPMediaItemPropertyRating (and actually it works ok with artist and song title).</p> <pre><code>2011-05-12 11:37:39.060 Radio3[1525:707] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'MPMediaPropertyPredicate cannot filter using the rating property.' </code></pre> <p>I google by MPMediaItemPropertyRating but it seems that I should find an alternative approach to filter by track rating. </p> <p>Can somebody give me a tip?</p> <p>thanks</p> <p>UPDATE: This is my code to solve this:</p> <pre><code>allMedia = [MPMediaQuery songsQuery]; //MPMediaPropertyPredicate *mpp1 = [MPMediaPropertyPredicate predicateWithValue:@"2" forProperty:MPMediaItemPropertyRating comparisonType:MPMediaPredicateComparisonEqualTo]; //MPMediaPropertyPredicate *mpp2 = [MPMediaPropertyPredicate predicateWithValue:@"Pop" forProperty:MPMediaItemPropertyGenre comparisonType:MPMediaPredicateComparisonContains]; //[allMedia addFilterPredicate:mpp1]; //[allMedia addFilterPredicate:mpp2]; //[myPlayer setQueueWithQuery:allMedia]; NSArray *itemsFromGenericQuery = [allMedia items]; NSMutableArray *mArray = [[NSMutableArray alloc] init]; int i = 0; int j=0; NSLog(@"itemCount: %d",[itemsFromGenericQuery count]); float playsQuery = sliderPlays.value; if(playsQuery == 20){playsQuery = 10000;} NSLog(@"sliderRating.value %f sliderPlays.value %.1f", [sliderRating value], playsQuery); while(i++ &lt; 1000){ int trackNumber = arc4random() % [itemsFromGenericQuery count]; MPMediaItem *song = [itemsFromGenericQuery objectAtIndex:trackNumber]; NSString *artistName = [song valueForProperty: MPMediaItemPropertyArtist]; NSString *title = [song valueForProperty: MPMediaItemPropertyTitle]; NSString *rating = [song valueForKey:MPMediaItemPropertyRating]; double lengh = [[song valueForProperty:MPMediaItemPropertyPlaybackDuration] doubleValue]; NSNumber *playCount = [song valueForKey:MPMediaItemPropertyPlayCount]; if ([rating intValue] &gt;= sliderRating.value &amp;&amp; [playCount intValue] &lt;= playsQuery) { if(j++ &gt; 50){break;} NSLog (@"tracknumber: %d j: %d artistName: %@ title: %@ lengh: %.1f rating: %@ playcount: %d",trackNumber, j, artistName, title, lengh, rating, [playCount intValue]); [mArray addObject:song]; } if(i++ &gt; 1000)break; } MPMediaItemCollection *itemCol = [[MPMediaItemCollection alloc] initWithItems:mArray]; [myPlayer setQueueWithItemCollection:itemCol]; [myPlayer setShuffleMode: MPMusicShuffleModeSongs]; [myPlayer setRepeatMode: MPMusicRepeatModeNone]; </code></pre>
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