Sorting mutable array by dictionary key

Question

I have already looked through a few answers using the various sorting methods of NSMutableArray, but for some reason they are not working for me.

I am just trying to sort the mutable array which contains dictionaries by the Delay key within each dictionary. However, the "sorted" array is the exact same as the original array.

By the way, it works fine if I create a dummy mutable array and populate it with dictionaries containing numbers, but for some reason it won't sort this mutable array that I am initializing.

What am I doing wrong?

Here's my code:

playlistCalls = [[NSMutableArray alloc] initWithArray:[currentPlaylist objectForKey:@"Tunes"]];

NSLog(@"original %@", playlistCalls);

NSSortDescriptor *delay = [NSSortDescriptor sortDescriptorWithKey:@"Delay" ascending:YES];
[playlistCalls sortUsingDescriptors:[NSArray arrayWithObject:delay]];

NSLog(@"sorted %@", playlistCalls);

Here's the array containing the dictionaries:

2012-06-04 15:48:09.129 MyApp[57043:f503] original (
        {
        Name = Test Tune;
        Delay = 120;
        Volume = 100;
    },
        {
        Name = Testes;
        Delay = 180;
        Volume = 100;
    },
        {
        Name = Testing;
        Delay = 60;
        Volume = 100;
    }
)

2012-06-04 15:48:09.129 MyApp[57043:f503] sorted (
        {
        Name = Test Tune;
        Delay = 120;
        Volume = 100;
    },
        {
        Name = Testes;
        Delay = 180;
        Volume = 100;
    },
        {
        Name = Testing;
        Delay = 60;
        Volume = 100;
    }
)

Joe · Accepted Answer · 2012-06-04 20:09:54Z

8

The code above is fine when I use NSNumbers in my dictionary. That leads me to believe that the Delay value is stored as strings in your dictionary. What you will need to do then is sort by the strings integerValue.

NSSortDescriptor *delay = 
   [NSSortDescriptor sortDescriptorWithKey:@"Delay.integerValue" ascending:YES];

answered Jun 4, 2012 at 20:09

Joe

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1 Comment

ZeNewb Over a year ago

Right you are... That did the trick. I need to go back and fix that. Thanks!

Omar Abdelhafith · Accepted Answer · 2012-06-04 20:06:54Z

1

Please try the following, it worked with me

NSDictionary *dic;
NSMutableArray *arr = [[NSMutableArray alloc] init];

dic = [NSDictionary dictionaryWithObjectsAndKeys:
        [NSNumber numberWithInt:120], @"Delay",
        [NSNumber numberWithInt:100], @"Volume",
       nil];
[arr addObject:dic];

dic = [NSDictionary dictionaryWithObjectsAndKeys:
       [NSNumber numberWithInt:160], @"Delay",
       [NSNumber numberWithInt:100], @"Volume",
       nil];
[arr addObject:dic];

dic = [NSDictionary dictionaryWithObjectsAndKeys:
       [NSNumber numberWithInt:100], @"Delay",
       [NSNumber numberWithInt:100], @"Volume",
       nil];
[arr addObject:dic];

NSSortDescriptor *sortDesc = [[NSSortDescriptor alloc] initWithKey:@"Delay" ascending:YES];
[arr sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];

answered Jun 4, 2012 at 20:06

Omar Abdelhafith

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2 Comments

ZeNewb Over a year ago

It works when you init the mutable array and add dictionaries like that, but why doesn't it work for my case when I already have a pre-populated mutable array? That's what I'm stuck on :\

ZeNewb Over a year ago

Thanks, but I was a dummy and stored them as strings. Joe caught it and gave me a fix. Thanks all the same!

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