QuickSort with Objective-C

QuickSort

- (NSArray *)quickSortWithArray:(NSArray *)array {
    
    if (array.count == 0) {
        return array;
    }
    
    // Use first item as pivot
    NSNumber *pivot = array[0];
    
    // Creat temp arrays to hold values
    NSMutableArray *leftArray = [NSMutableArray array];
    NSMutableArray *rightArray = [NSMutableArray array];
    
    // All elements less than pivot go to left array
    // All elements greater than pivot go to right array
    for (NSInteger i = 1; i < array.count; i++) {
        NSNumber *item = array[i];
        if (item.integerValue < pivot.integerValue) {
            [leftArray addObject:item];
        } else {
            [rightArray addObject:item];
        }
    }
    
    // Recursively build merged arrays
    NSArray *leftMerged = [self quickSortWithArray:leftArray];
    NSArray *rightMerged = [self quickSortWithArray:rightArray];
    
    // Build final array
    NSMutableArray *finalArray = [NSMutableArray array];
    [finalArray addObjectsFromArray:leftMerged];
    [finalArray addObject:pivot];
    [finalArray addObjectsFromArray:rightMerged];
    
    return finalArray;
}

This assumes an array of NSNumber objects.