Imansible trovare un mapping di oggetti per keyPath: ''

Sto cercando di utilizzare RestKit per comunicare con un servizio Web che fornisce notizie. Ho studiato questo pezzo di documentazione e basato su quello scritto questo codice

// // NewsViewController_iPhone.m #import "NewsViewController_iPhone.h" #import <RestKit/RestKit.h> #import <RestKit/CoreData/CoreData.h> #import "NewsPost.h" @implementation NewsViewController_iPhone - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; if (self) { RKObjectManager* manager = [RKObjectManager objectManagerWithBaseURL:@"http://192.168.0.197:3000"]; RKObjectMapping* newsPostMapping = [RKObjectMapping mappingForClass:[NewsPost class]]; [newsPostMapping mapKeyPath:@"title" toAttribute:@"title"]; [newsPostMapping mapKeyPath:@"body" toAttribute:@"body"]; [newsPostMapping mapKeyPath:@"image" toAttribute:@"image"]; [newsPostMapping mapKeyPath:@"date" toAttribute:@"date"]; [manager.mappingProvider setMapping:newsPostMapping forKeyPath:@"news_items"]; [manager loadObjectsAtResourcePath:@"/news.json"delegate:self]; } return self; } - (void)dealloc { [super dealloc]; } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } #pragma mark - View lifecycle - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view from its nib. } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. // eg self.myOutlet = nil; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } - (void)objectLoader:(RKObjectLoader *)objectLoader didFailWithError:(NSError *)error { NSString *stringError = @"Ett problem uppstod vid hämtning av nyheter"; NSLog(stringError); /*UIAlertView *alert = [[UIAlertView alloc] initWithTitle:stringError]; [alert show]; [alert release];*/ } - (void)request:(RKRequest*)request didLoadResponse: (RKResponse*)response { if ([request isGET]) { if ([response isOK]) { NSLog(@"Retrieved JSON: %@", [response bodyAsString]); } } else if ([request isPOST]) { if ([response isJSON]) { NSLog(@"Got a JSON response back from our POST!"); } } } - (void)objectLoader:(RKObjectLoader *)objectLoader didLoadObjects:(NSArray *)objects { NSLog(@"%@", objects); } 

Ottengo il seguente output del registro

 2011-10-10 15:57:40.807 App[94979:207] Retrieved JSON: {"news_posts":[{"title":"test title","body":"test body","image":"/uploads/post/image/1/app_iPhone.png","date":"10/10 2011"}]} 2011-10-10 15:57:40.808 App[94979:7507] W restkit.object_mapping:RKObjectMapper.m:74 Adding mapping error: Could not find an object mapping for keyPath: '' 2011-10-10 15:57:40.809 App[94979:7507] E restkit.network:RKObjectLoader.m:190 Encountered errors during mapping: Could not find an object mapping for keyPath: '' 2011-10-10 15:57:40.809 App[94979:7507] Ett problem uppstod vid hämtning av nyheter 

Ma non ha molto senso per me. Qualcuno sa quale potrebbe essere il problema?

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