SelectionSort

SelectionSort.m

//
//  SelectionSort.m
//  KIObjcAlgorithms
//
//  Created by Keita on 9/11/15.
//  Copyright © 2015 Keita Ito. All rights reserved.
//

#import "SelectionSort.h"

@implementation SelectionSort

- (void)selectionSort:(NSMutableArray *)array {
    for (NSUInteger i = 0; i < array.count; i++) {
        NSUInteger minIndex = [self minimumIndexOfArray:array startIndex:i];
        [self swapElementsOfArray:array WithIndex:i andAnotherIndex:minIndex];
    }
}


- (void)swapElementsOfArray:(NSMutableArray *)array WithIndex:(NSUInteger)firstIndex andAnotherIndex:(NSUInteger)secondIndex {
    NSNumber *temp = array[firstIndex];
    array[firstIndex] = array[secondIndex];
    array[secondIndex] = temp;
}

- (NSUInteger)minimumIndexOfArray:(NSMutableArray *)array startIndex:(NSUInteger)startIndex {
    
    NSUInteger minIndex = startIndex;
    NSNumber *minValue = array[startIndex];
    
    for (NSUInteger i = minIndex + 1; i < array.count; i++) {
        if (array[i] < minValue) {
            minIndex = i;
            minValue = array[i];
        }
    }
    
    return minIndex;
}

@end

Reference: https://www.khanacademy.org/computing/computer-science/algorithms/sorting-algorithms/p/challenge-implement-selection-sort