RestKit/Code/Support/NSArray+RKAdditions.m

//
//  NSArray+RKAdditions.m
//  RestKit
//
//  Created by Blake Watters on 4/10/12.
//  Copyright (c) 2012 RestKit. All rights reserved.
//

#import "NSArray+RKAdditions.h"

@implementation NSArray (RKAdditions)

- (NSArray *)sectionsGroupedByKeyPath:(NSString *)keyPath
{
    // Code adapted from: https://gist.github.com/1243312
    NSMutableArray *sections = [NSMutableArray array];

	// If we don't contain any items, return an empty collection of sections.
	if([self count] == 0) {
		return sections;
    }

	// Create the first section and establish the first section's grouping value.
	NSMutableArray *sectionItems = [NSMutableArray array];
	id currentGroup = [[self objectAtIndex:0] valueForKeyPath:keyPath];
    
	// Iterate over our items, placing them in the appropriate section and
	// creating new sections when necessary.
	for (id item in self) {
		// Retrieve the grouping value from the current item.
		id itemGroup = [item valueForKeyPath:keyPath];

		// Compare the current item's grouping value to the current section's
		// grouping value.
		if (![itemGroup isEqual:currentGroup] && (currentGroup != nil || itemGroup != nil)) {
			// The current item doesn't belong in the current section, so
			// store the section we've been building and create a new one,
			// caching the new grouping value.
			[sections addObject:sectionItems];
			sectionItems = [NSMutableArray array];
			currentGroup = itemGroup;
		}

		// Add the item to the appropriate section.
		[sectionItems addObject:item];
	}

	// If we were adding items to a section that has not yet been added
	// to the aggregate section collection, add it now.
	if ([sectionItems count] > 0) {
		[sections addObject:sectionItems];
    }
    
	return sections;
}

@end