RestKit is an iOS framework that simplifies communication with RESTful web services. It includes a networking layer for sending and receiving HTTP requests, object mapping for serializing responses to Objective-C objects, integration with Core Data for storage, and pluggable parsing layers for different data formats like JSON and XML. RestKit handles common tasks like authentication, request queuing, response parsing, and object lifecycles to provide a complete solution for working with REST APIs in iOS applications.

1. RESTful iOS with RestKit
Taras Kalapun
Sergey Kluev

2. What is RestKit?
2

3. 3

4. 4

5. RestKit Architecture
• Network Layer
• Object Mapping
• Core Data
• Pluggable parsing layer
• Integration Points
5

6. Network Layer
6

7. Key Concepts
• RKClient - Your user agent
• Base URLs and Resource Paths
• RKRequest & RKResponse - The HTTP
lifecycle
• RKRequestQueue - A lightweight queue
implementation
• RKParams - Multi-part MIME requests
• Reachability - Detecting offline/online status
7

8. RKClient
• Sending Asynchronous Requests
1 – get:delegate:
2 – get:queryParams:delegate:
3 – post:params:delegate:
4 – put:params:delegate:
5 – delete:delegate:
8

9. Initializing RKClient
- (void)initRKClient {
! // Initialize with a Base URL
! RKClient* client = [RKClient clientWithBaseURL:@"http://restkit.org"];
!
! // Setup HTTP AUTH
! client.username = @"restkit";
! client.password = @"rocks";
!
! // Set an app-wide API key HTTP header
! [client setValue:@"123456" forHTTPHeaderField:@"X-RESTKIT-API-KEY"];
!
! // The first initialized RKClient becomes
! // the sharedClient instance
! [[RKClient sharedClient] isNetworkAvailable];
}
9

10. Sending Requests
- (void)sendRequest {
! // Send an HTTP GET request to 'http://restkit.org/contacts'
! [[RKClient sharedClient] get:@"/contacts" delegate:self];
}
// RKRequestDelegate methods
- (void)request:(RKRequest*)request didLoadResponse:(RKResponse*)response {
! NSLog(@"Yay! We Got a response");
}
- (void)request:(RKRequest*)request didFailLoadWithError:(NSError*)error {
! NSLog(@"Oh no! Error: %@", [error localizedDescription]);
}
10

11. Processing Responses
- (void)sendRequest {
! // Send an HTTP GET request to 'http://restkit.org/contacts'
! [[RKClient sharedClient] get:@"/contacts" delegate:self];
}
- (void)request:(RKRequest*)request didLoadResponse:(RKResponse*)response
{
! NSLog(@"Request Headers: %@", [response allHeaderFields]);
! NSLog(@"Cookies: %@", [response cookies])
!
! if ([response isSuccessful]) {
! ! // Response status was 200..299
! ! if ([response isCreated] && [response isJSON]) {
! ! ! // Looks like we have a 201 response of type 'application/
json'
! ! ! NSLog(@"The JSON is %@", [response bodyAsJSON]);
! ! }
! } else if ([response isError]) {
! ! // Response status was either 400..499 or 500..599
! ! NSLog(@"HTTP error, status Code: %@", [response
localizedStatusCodeString]);
! }
}
11

12. Requests with Parameters
- (void)sendRequestWithParams {
! // Simple params
! NSDictionary* paramsDictionary = [NSDictionary
dictionaryWithObjectsAndKeys:
! ! ! ! ! ! ! ! ! @"User", @"name",
! ! ! ! ! ! ! ! ! @"Ciklum", @"company", nil];
! [[RKClient sharedClient] post:@"/contacts" params:paramsDictionary
delegate:self];
!
! // Multi-part params via RKParams!
! RKParams* params = [RKParams paramsWithDictionary:paramsDictionary];
! NSData* imageData = UIImagePNGRepresentation([UIImage
imageNamed:@"picture.jpg"]);
! [params setData:imageData MIMEType:@"image/png" forParam:@"photo"];
! [params setFile:@"bio.txt" forParam:@"attachment"];
! [[RKClient sharedClient] post:@"/contacts" params:params delegate:self];
}
12

13. Reachability
- (void)demoReachability {
! // Check if the network is available
! [[RKClient sharedClient] isNetworkAvailable];
!
! // Register for changes in network availability
! NSNotificationCenter* center = [NSNotificationCenter defaultCenter];
! [center addObserver:self selector:@selector(reachabilityDidChange:)
name:RKReachabilityStateChangedNotification object:nil];
}
- (void)reachabilityDidChange:(NSNotification*)notification {
! RKReachabilityObserver* observer = (RKReachabilityObserver*)
[notification object];
! RKReachabilityNetworkStatus status = [observer networkStatus];
! if (RKReachabilityNotReachable == status) {
! ! NSLog(@"No network access!");
! } else if (RKReachabilityReachableViaWiFi == status) {
! ! NSLog(@"Online via WiFi!");
! } else if (RKReachabilityReachableViaWWAN == status) {
! ! NSLog(@"Online via Edge or 3G!");
! }
}
13

14. Object Mapping 2.0
14

15. Modeling a RESTful Service
"user": {
"id":31337,
"name":"Blake Watters",
"screen_name":"Blake Watters"
}
@interface RKTUser : NSObject
@property (nonatomic, retain) NSNumber* userID;
@property (nonatomic, retain) NSString* name;
@property (nonatomic, retain) NSString* screenName;
@end
15

16. "created_at":"Sat Mar 05 13:39:09 +0000 2011",
"favorited":false,
"id":44029179364253700,
"in_reply_to_screen_name":"JustJenFelice",
"text":"@JustJenFelice Be sure to join the Google Group and
reach out if you need any support!",
"user":{
"id":208727870,
"name":"RestKit",
"screen_name":"RestKit",
}
16

17. Initializing the Object Mapping
17

18. // Init RestKit
RKObjectManager* objectManager = [RKObjectManager
objectManagerWithBaseURL:@"http://twitter.com"];
// Setup our object mappings
RKObjectMapping* userMapping = [RKObjectMapping mappingForClass:
[RKTUser class]];
[userMapping mapKeyPath:@"id" toAttribute:@"userID"];
[userMapping mapKeyPath:@"screen_name" toAttribute:@"screenName"];
[userMapping mapAttributes:@"name", nil];
18

19. // Setup our object mappings
RKObjectMapping* statusMapping = [RKObjectMapping mappingForClass:
[RKTStatus class]];
[statusMapping mapKeyPathsToAttributes:@"id", @"statusID",
@"created_at", @"createdAt",
@"text", @"text",
@"url", @"urlString",
@"in_reply_to_screen_name", @"inReplyToScreenName",
@"favorited", @"isFavorited",
nil];
[statusMapping mapRelationship:@"user" withObjectMapping:userMapping];
// Update date format so that we can parse Twitter dates properly
// Wed Sep 29 15:31:08 +0000 2010
[statusMapping.dateFormatStrings addObject:@"E MMM d HH:mm:ss Z y"];
// Register our mappings with the provider
[objectManager.mappingProvider setObjectMapping:userMapping
forKeyPath:@"user"];
[objectManager.mappingProvider setObjectMapping:statusMapping
forKeyPath:@"status"];
19

20. Loading Remote Objects
- (void)loadTimeline {
// Load the object model via RestKit!
RKObjectManager* objectManager = [RKObjectManager sharedManager];
RKObjectMapping* statusMapping = nil;
// Twitter returns statuses as a naked array in JSON, so we instruct
the loader to user the appropriate object mapping
if ([objectManager.acceptMIMEType isEqualToString:RKMIMETypeJSON]) {
statusMapping = [objectManager.mappingProvider
objectMappingForKeyPath:@"status"];
}
[objectManager loadObjectsAtResourcePath:@"/status/user_timeline/
RestKit" objectMapping:statusMapping delegate:self];
}
- (void)objectLoader:(RKObjectLoader*)objectLoader didLoadObjects:
(NSArray*)objects {
! NSLog(@"Loaded statuses: %@", objects);
}
20

21. Configuring the Router
- (void)configureRouter {
! [objectManager.router routeClass:[Contact class] toResourcePath:@"/contacts/
(contactID)"];
! [objectManager.router routeClass:[Contact class] toResourcePath:@"/contacts"
forMethod:RKRequestMethodPOST];
}
21

22. RESTful Object Manipulation
// Create a new Contact
- (void)createObject {
! Contact* contact = [Contact new];
! contact.name = @"RestKit User";
! contact.email = @"user@restkit.org";
!
! // POST to /contacts
! [[RKObjectManager sharedManager] postObject:contact delegate:self];
}
// Edit Contact with ID 12345
- (void)editObject {
! Contact* contact = [Contact new];
! contact.contactID = [NSNumber numberWithInt:12345];
! contact.name = @"New Name";
!
! // POST to /contacts/12345
! [[RKObjectManager sharedManager] putObject:contact delegate:self];
}
// Delete Contact with ID 321
- (void)deleteObject {
! Contact* contact = [Contact new];
! contact.contactID = [NSNumber numberWithInt:321];
!
! // DELETE to /contacts/321
! [[RKObjectManager sharedManager] deleteObject:contact delegate:self];!
}
22

23. Core Data
23

24. Configuring CoreData
#import <RestKit/CoreData/CoreData.h>
- (void)configureObjectStore {
// Initialize the RestKit Object Manager
RKObjectManager* objectManager = [RKObjectManager
objectManagerWithBaseURL:@"http://restkit.org"];
!
// Initialize object store
// We are using the Core Data support, so we have initialized a managed
object store backed
// with a SQLite database.
objectManager.objectStore = [RKManagedObjectStore
objectStoreWithStoreFilename:@"Contacts.sqlite"];
}
24

25. Mapping
RKManagedObjectMapping* userMapping = [RKManagedObjectMapping
mappingForEntityWithName:@"RKTUser"];
userMapping.primaryKeyAttribute = @"userID";
[userMapping mapKeyPath:@"id" toAttribute:@"userID"];
[userMapping mapKeyPath:@"screen_name" toAttribute:@"screenName"];
[userMapping mapAttributes:@"name", nil];
25

26. Working with Core Data
// Adapted from https://github.com/magicalpanda/MagicalRecord
// Get all the Contacts
NSArray* contacts = [Contact allObjects];
!
// Count the Contacts
NSError* error = nil;
NSUInteger count = [Contact count:&error];
!
// Find Contact by primary key
NSNumber* contactID = [NSNumber numberWithInt:12345];
Contact* somebody = [Contact objectWithPrimaryKeyValue:contactID];
!
// Find Contacts with criteria
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"name
contains[cd] 'restkit'"];
NSArray* matches = [Contact objectsWithPredicate:predicate];
26

27. Database Seeding
NSString *seedDatabaseName = nil;
NSString *databaseName = RKDefaultSeedDatabaseFileName;
objectManager.objectStore = [RKManagedObjectStore
objectStoreWithStoreFilename:databaseName
usingSeedDatabaseName:seedDatabaseName managedObjectModel:nil
delegate:self];
RKManagedObjectSeeder* seeder = [RKManagedObjectSeeder
objectSeederWithObjectManager:objectManager];
// Seed DB with instances of RKTStatus from a snapshot of the RestKit
Twitter timeline
[seeder seedObjectsFromFile:@"restkit.json"
withObjectMapping:statusMapping];
// Seed DB with RKTUser objects. The class will be inferred via element
registration
[seeder seedObjectsFromFiles:@"users.json", nil];
// Finalize the seeding and output a helpful informational message
[seeder finalizeSeedingAndExit];
27

28. Pluggable parsing layer
• JSON
- SBJSON
- NXJSON
- YAJL
- JSONKit
• XML
28

29. // Adapted from https://github.com/magicalpanda/MagicalRecord
// Get all the Contacts
NSArray* contacts = [Contact allObjects];
!
// Count the Contacts
NSError* error = nil;
NSUInteger count = [Contact count:&error];
!
// Find Contact by primary key
NSNumber* contactID = [NSNumber numberWithInt:12345];
Contact* somebody = [Contact objectWithPrimaryKeyValue:contactID];
!
// Find Contacts with criteria
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"name
contains[cd] 'restkit'"];
NSArray* matches = [Contact objectsWithPredicate:predicate];
29

30. Integration Points
Three20
Ruby on Rails
30

31. http://restkit.org/
http://twitter.com/restkit
http://github.com/RestKit/RestKit

32. ?