RestKit with my JSON data is not working - mysql

Question

I'm trying to understand the restkit 0.22. I got some tutorials from different blogs and youtubes. I ended up with mixed up code.
Could anyone please help me with this, I really need it to work for my project.
I created Core Data Model with entities Songs.xcdatamodeld
I have a json that comes from my mySQL db:
[{"SongID":"1","SongTitle":"Song1","PerformerName":"Performer1","SongURL":"http://mysite/mysongs/1.mp3","PerformerPic":"PerfPic1.png"},
{"SongID":"2","SongTitle":"Song2","PerformerName":"Performer2","SongURL":"http://mysite/mysongs/2.mp3","PerformerPic":"PerfPic2.png"},
{"SongID":"3","SongTitle":"Song3","PerformerName":"Performer3","SongURL":"http://mysite/mysongs/3.mp3","PerformerPic":"PerfPic3.png"}]
in AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
RKObjectManager *objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:http://mysite]];
NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:#"Songs" ofType:#"momd"]];
//Initialize managed object store
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL ] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
objectManager.managedObjectStore = managedObjectStore;
[RKObjectManager sharedManager].requestSerializationMIMEType = RKMIMETypeJSON;
[RKMIMETypeSerialization registeredMIMETypes];
[objectManager setAcceptHeaderWithMIMEType:#"application/json"];
RKEntityMapping* mapping = [RKEntityMapping mappingForEntityForName:#"Songs"
inManagedObjectStore:[RKObjectManager sharedManager].managedObjectStore];
mapping.identificationAttributes = #[#"songID"];
[mapping addAttributeMappingsFromDictionary:#{#"id" : #"SongID",
#"songTitle" : #"SongTitle",
#"performerName" : #"PerformerName",
#"songURL" : #"SongURL",
#"performerPic" : #"PerformerPic"}];
return YES;
}
in TableView Controller:
- (void)viewDidLoad
{
[super viewDidLoad];
[RKObjectManager.sharedManager getObjectsAtPath:#"/api.php"
parameters:nil
success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult)
{
self.Songs = [mappingResult array];
NSLog(#"It Worked: %#", self.Songs);
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
NSLog(#"It Failed: %#", error);
}];
}
This is the error I'm getting:
GET 'http://mysite/api.php' (200 OK / 0 objects) [request=3.5566s mapping=0.0000s
total=3.5627s]: Error Domain=org.restkit.RestKit.ErrorDomain Code=1001
"No response descriptors match the response loaded." UserInfo=0xb5920b0
{NSErrorFailingURLStringKey=http://mysite/api.php, NSLocalizedFailureReason=A 200
response was loaded from the URL 'http://mysite/api.php', which failed to match all (0)
response descriptors:, NSLocalizedDescription=No response descriptors match the response
loaded., keyPath=null, NSErrorFailingURLKey=http://mysite/api.php,
NSUnderlyingError=0xb5921b0 "No mappable object representations were found at the key
paths searched."}

Answer 1

First, you don't seem to be creating the managed object contexts as part of your setup code. This will likely cause you issues after you fix your 'main' issue:
Your main issue is quite clearly described in the error message:
which failed to match all (0) response descriptors
I.e. You haven't created any response descriptors.
The Object-mapping guide walks you through the mapping and descriptor creation process (and includes lots more details to boot).
Start with something like:
RKResponseDescriptor *rd = [RKResponseDescriptor responseDescriptorWithMapping:mapping pathPattern:nil keyPath:nil statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
then add the mapping to the object manager.
(ensure you're calling createManagedObjectContexts somewhere).