Extension for category NSMutableArray Objective-C

Question

I am a beginner programmer and I was given the assignment to write an extension to the category NSMutableArray. In googled it, i found very little information and did not understand how to do it. I need to write an extension to Shell sort. I could use NSSortDescriptor, but expansion should be given the sort algorithm, a standard NSSortDescriptor method is not applicable for this. If there is some sort of a normal user Associative References and how to use it, it is really helped. Because, what I found - is not for me.

Answer 1

So here it is...

NSMutableArray+Sort.h

#import <Foundation/Foundation.h>
@interface NSMutableArray (Sort)

    -(void)sortArrayUsingShellSort;

@end

NSMutableArray+Sort.m

#import "NSMutableArray+Sort.h"
@implementation NSMutableArray (Sort)

    -(void)sortArrayUsingShellSort
    {
         // tasks
         // #1. access the unsorted array using self
         // #2. sort the array using your shell sort, no one gonna do that for you, you have to do that yourself. Re-arrange the items or the array.

    }

@end

some useful link for shell sort

1. Tutorials point
2. interactivepuython
3. Wikipedia
4. Toptal

Into your main.m

#import <Foundation/Foundation.h> // not necessary actually, as it is already imported into our NSMutableArray+Sort.h
#import "NSMutableArray+Sort.h"

int main(int argc, char * argv[]) {

    NSMutableArray *myArray = [[NSMutableArray alloc] initWithArray:@[
                                            [NSNumber numberWithInt:10],
                                            [NSNumber numberWithInt:3],
                                            [NSNumber numberWithInt:4],
                                            [NSNumber numberWithInt:15]
                                            ]];


    NSLog(@"array before sorting %@", myArray);

    //here goes your sorting category function call
    [myArray sortArrayUsingShellSort];

    NSLog(@"array after sorting %@", myArray);
}