Sort A Dictionary By Value Of Each Key-Value Pair

May 16, 2012

You can sort the values in a dictionary using the method keysSortedByValueUsingSelector:. The result is an array of keys from the dictionary, which represent the sorted values of the key-value pair.

Let’s say for example that you have a dictionary that has key-value pairs with an account name and balance:

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:
              [NSNumber numberWithDouble:-100.00], @"Account1",
              [NSNumber numberWithDouble:72.99], @"Account2",
              [NSNumber numberWithDouble:30.89], @"Account3",
              [NSNumber numberWithDouble:200.74], @"Account4", nil];

Sorting the dictionary is as simple as follows:

NSArray *sortedArray = [dict keysSortedByValueUsingSelector:@selector(compare:)];
 
NSLog(@"dict: %@", sortedArray);

The output would look as follows:

dict: (
    Account1,
    Account3,
    Account2,
    Account4
)

The same works equally as well if the value is a string:

NSDictionary *dict2 = [NSDictionary dictionaryWithObjectsAndKeys:
              @"ISBN-123", @"Data Structures",
              @"ISBN-101", @"Computer Graphics",
              @"ISBN-444", @"Boolean Logic",
              @"ISBN-222", @"Artificial Intelligence", nil];
 
NSArray *sortedArray = [dict2 keysSortedByValueUsingSelector:@selector(compare:)];

The sorted array of keys would are shown below:

dict: (
    "Computer Graphics",
    "Data Structures",
    "Artificial Intelligence",
    "Boolean Logic"
)