Escaping punctuation, and 'The' prefix in song titles when collating a MPMediaQuery

Question

The code works and populates the table with sections, but it has a flaw: It doesn't escape punctuation and 'The' prefixes in song titles, just like how the native music app does.

Would really appreciate some guidance on how I should go about doing this.

- (void)viewDidLoad
{
    [super viewDidLoad];
    MPMediaQuery *songQuery = [MPMediaQuery songsQuery];
    self.songsArray = [songQuery items];
    self.sectionedSongsArray = [self partitionObjects:self.songsArray collationStringSelector:@selector(title)];
}

- (NSArray *)partitionObjects:(NSArray *)array collationStringSelector:(SEL)selector
{
    UILocalizedIndexedCollation *collation = [UILocalizedIndexedCollation currentCollation];
    NSInteger sectionCount = [[collation sectionTitles] count];
    NSMutableArray *unsortedSections = [NSMutableArray arrayWithCapacity:sectionCount];
    for(int i = 0; i < sectionCount; i++)
    {
        [unsortedSections addObject:[NSMutableArray array]];
    }
    for (id object in array)
    {
        NSInteger index = [collation sectionForObject:object collationStringSelector:selector];
        [[unsortedSections objectAtIndex:index] addObject:object];
    }
    NSMutableArray *sections = [NSMutableArray arrayWithCapacity:sectionCount];
    for (NSMutableArray *section in unsortedSections)
    {
        [sections addObject:[collation sortedArrayFromArray:section collationStringSelector:selector]];
    }
    return sections;
}

score 5 · Accepted Answer · answered Nov 06 '12 at 03:33

5

I completely overlooked this. The answer here is to simply use MPMediaQuerySection. The Apple docs are there for a reason!

answered Nov 06 '12 at 03:33

sooper

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Could you share how you implemented this? I'm stuck on the same thing and I'm going crazy! And does it work for lists of other MPMediaItems/MPMediaCollections? Thanks – topLayoutGuide Feb 07 '13 at 13:30
I wrote my whole media library with the partitionObjects method. It's 'quick' to an extent, but this is a LOT quicker with MPMediaQuerySection. Some help would be much appreciated! – topLayoutGuide Feb 08 '13 at 12:35

score 2 · Answer 2 · answered Mar 29 '13 at 08:35

Cocotutch -

Here's the implementation that I used to index a query containing all the songs in my music library:

MPMediaQuery *allSongsQuery = [MPMediaQuery songsQuery];

// Fill in the all songs array with all the songs in the user's media library
allSongsArray = [allSongsQuery items];

allSongsArraySections = [allSongsQuery itemSections];

allSongsArraySections is an NSArray of MPMediaQuerySection, each of which has a title and a range. The NSArray object for section zero (with title @"A" in my case) has range.location of 0 and range.length of 158.

I return the range.length value for each section when numberOfRowsInSection is called for my UITableView. I use the range.location value in cellForRowAtIndexPath as the starting row of the section, and then add indexPath.row to it in order to arrive at the cell I need to return from my allSongsArray.

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
....
    // Return the number of rows in the section.
    MPMediaQuerySection *allSongsArraySection = globalMusicPlayerPtr.allSongsArraySections[section];
    return allSongsArraySection.range.length;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
...
    MPMediaQuerySection *allSongsArraySection = globalMusicPlayerPtr.allSongsArraySections[indexPath.section];
    rowItem = [globalMusicPlayerPtr.allSongsArray objectAtIndex:allSongsArraySection.range.location + indexPath.row];
....
}

Before using this I had tried to match the native music player's implementation by writing my own, and it didn't behave quite identically. Not only that, but the native indexing is MUCH faster!

The only caveat with the `MPMediaQuerySection` route is that it doesn't support foreign languages (for devices where English is not the default language and their music library contains info with foreign characters). So often the index key/section titles are flooded with `#` and table is unordered. This is where the `partitionObjects` method wins. — sooper, Mar 29 '13 at 23:28

Escaping punctuation, and 'The' prefix in song titles when collating a MPMediaQuery

2 Answers2