NSArray Extensions

NSArray+NSArrayExtensions.h

//
//  NSArray+NSArrayExtensions.h
//  ArrayFunctions
//
//  Created by Geoff Armstrong on 11/4/15.
//  Copyright © 2015 Geoff Armstrong. All rights reserved.
//

#ifndef NSArray_NSArrayExtensions_h
#define NSArray_NSArrayExtensions_h

@interface NSArray (NSArrayExtensions)

/**
 Rotates an array by index elements
 @param index The index to rotate the array to
 @return A rotated array
 */
- (instancetype) rotateArrayToIndex: (int) index;

/**
 Sorts an array of NSString alphabetically using optimized bubble sort
 @return The sorted array
 */
- (instancetype) sortStringArray;

/**
 Sorts an array of NSNumber in increasing order using optimized bubble sort
 @return The sorted array
 */
- (instancetype) sortNumberArray;

@end
#endif /* NSArray_NSArrayExtensions_h */

NSArray+NSArrayExtensions.m

//
//  NSArray+NSArrayExtensions.m
//  ArrayFunctions
//
//  Created by Geoff Armstrong on 11/4/15.
//  Copyright © 2015 Geoff Armstrong. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "NSArray+NSArrayExtensions.h"

@implementation NSArray (NSArrayExtensions)

- (instancetype) rotateArrayToIndex:(int)n {
    NSMutableArray *newArray = [NSMutableArray arrayWithArray:self];
    
    for (int i=0; i < n; i++){
        NSObject *theObject = [newArray objectAtIndex:0];
        [newArray removeObjectAtIndex:0];
        [newArray addObject:theObject];
    }
    return newArray;
}

- (instancetype) sortStringArray {
    NSMutableArray *sortedArray = [NSMutableArray arrayWithArray: self];
    
    //Keep track of how many loops have been made, the last item is not required for each subsequent pass.
    int loopCount = 0;
    //Initialize didSwap to YES to step into the loop
    BOOL didSwap = YES;
    //Continue until no changes are made to the array
    while (didSwap) {
        didSwap = NO;
        for ( int i=1; i < sortedArray.count - loopCount; i++ ) {
            NSString *stringA = [sortedArray objectAtIndex:i - 1];
            NSString *stringB = [sortedArray objectAtIndex:i];
            
            unichar characterA = [stringA characterAtIndex:0];
            unichar characterB = [stringB characterAtIndex:0];
            
            int charStep = 1;
            while (characterA == characterB) {
                if (charStep < [stringA length]) {
                    characterA = [stringA characterAtIndex:charStep];
                }
                if (charStep < [stringB length]) {
                    characterB = [stringB characterAtIndex:charStep];
                }
                //If we have reached the end of both strings, they are the same.
                if (charStep >= stringA.length && charStep >= stringB.length) {
                    break;
                }
                charStep++;
            }
            
            //If the character code for A is greater than the character code for B then swap the two items
            if (characterA > characterB) {
                [sortedArray removeObjectAtIndex:i];
                [sortedArray insertObject:stringB atIndex:i - 1];
                didSwap = YES;
            }
        }
        loopCount++;
    }
    
    return sortedArray;
}

- (instancetype) sortNumberArray {
    NSMutableArray *sortedArray = [NSMutableArray arrayWithArray: self];
    
    //Keep track of how many loops have been made, the last item is not required for each subsequent pass.
    int loopCount = 0;
    //Initialize didSwap to YES to step into the loop
    BOOL didSwap = YES;
    //Continue until no changes are made to the array
    while (didSwap) {
        didSwap = NO;
        for ( int i=1; i < sortedArray.count - loopCount; i++ ) {
            NSNumber *numberA = [sortedArray objectAtIndex:i - 1];
            NSNumber *numberB = [sortedArray objectAtIndex:i];
            
            //If the number for A is greater than the number for B then swap the two items
            if ([numberA isGreaterThan:numberB]) {
                [sortedArray removeObjectAtIndex:i];
                [sortedArray insertObject:numberB atIndex:i - 1];
                didSwap = YES;
            }
        }
        loopCount++;
    }
    
    return sortedArray;
}

@end