we often come to a situation where we have to create the dictionary based on the alphabetic order.

So here is the program for creating a Dictionary with first letter of the array element. array element First letter is a key for adding the element in Dictionary

#import "ViewController.h"
@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];


NSMutableArray myDataArray=[[NSMutableArray alloc]initWithObjects:@"anane",@"bnane",@"cnane",@"anane1",@"bnane1",@"cnane1",@"anane2",@"bnane2",@"cnane2",@"anane3",@"bnane3",@"cnane3",@"anane4",@"bnane4",@"cnane5",@"anane6",@"bnane6",@"cnane6",@"madj",@"iuer",@"dkdk", nil];

 NSMutableDictionary dictForKeyAndValues= [NSMutableDictionary dictionary];

    for (NSString *word in myDataArray) {
        NSString *firstLetter = [[word substringToIndex:1] uppercaseString];

        NSMutableArray *letterList = [dictForKeyAndValues objectForKey:firstLetter];
        if (!letterList) {

            NSLog(@"ye kab chalega");
            letterList = [NSMutableArray array];
            [dictForKeyAndValues setObject:letterList forKey:firstLetter];
        }

        [letterList addObject:word];
    }
    NSLog(@"%@", dictForKeyAndValues);
}


@end

Output:

{
    A =     (
        anane,
        anane1,
        anane2,
        anane3,
        anane4,
        anane6
    );
    B =     (
        bnane,
        bnane1,
        bnane2,
        bnane3,
        bnane4,
        bnane6
    );
    C =     (
        cnane,
        cnane1,
        cnane2,
        cnane3,
        cnane5,
        cnane6
    );
    D =     (
        dkdk
    );
    I =     (
        iuer
    );
    M =     (
        madj
    );
}