core-data - Restkit 在核心数据映射之前截断 db

Question

我正在使用restkit来映射一个带有核心数据的json

每次用户启动应用程序时，我都需要调用一个例程。

如果服务器更新了要发送的数据，我需要下载它们，截断我的表并将数据插入表中，如果服务器什么也没给我发送，我不必什么都不做。

显然，我只想在确定新数据已下载时才截断当前数据，而不是之前

我怎样才能做到这一点？

这是我的代码：

NSURL *endpoint = [NSURL URLWithString:kBaseURL];
RKObjectManager* objectManager = [RKObjectManager managerWithBaseURL:endpoint];

[objectManager.HTTPClient setAuthorizationHeaderWithToken:@"username:my-token-12345"];
objectManager.managedObjectStore = [RKManagedObjectStore defaultStore];

[RKObjectManager setSharedManager:objectManager];

RKEntityMapping *entityMapping = [RKEntityMapping mappingForEntityForName:@"Medic" inManagedObjectStore:objectManager.managedObjectStore];
[entityMapping addAttributeMappingsFromDictionary:@{
                                                    @"identifier":          @"identifier",
                                                    @"name":                @"name",
                                                    @"surname":             @"surname",
                                                    @"personalAddress":     @"personalAddress",
                                                    @"hospital":            @"hospital",
                                                    @"hospitalAddress":     @"hospitalAddress",
                                                    @"oldDigitalAgreement": @"oldDigitalAgreement",
                                                    @"oldPaperAgreement":   @"oldPaperAgreement"}];
entityMapping.identificationAttributes = @[@"identifier"];

RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor
                                            responseDescriptorWithMapping:entityMapping
                                            method:RKRequestMethodAny
                                            pathPattern:nil
                                            keyPath:nil
                                            statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

[objectManager addResponseDescriptor:responseDescriptor];


[[RKObjectManager sharedManager] getObjectsAtPath:kregistryURL
                                       parameters:nil
                                          success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
                                              // done
                                          }
                                          failure:^(RKObjectRequestOperation *operation, NSError *error) {
                                              UIAlertView * alertView = [[UIAlertView alloc]initWithTitle:NSLocalizedString(@"attention", nil) message:NSLocalizedString(@"communication.genericerror.title", nil) delegate:nil cancelButtonTitle:nil otherButtonTitles:@"Ok", nil];
                                              [alertView show];
                                          }
 ];

Wain回答后的解决方案

[objectManager addFetchRequestBlock:^NSFetchRequest *(NSURL *URL) {
    RKPathMatcher* pathMatcher = [RKPathMatcher pathMatcherWithPattern:kregistryURL];

    NSDictionary *dic = nil;
    if ([pathMatcher matchesPath:[URL relativePath] tokenizeQueryStrings:YES parsedArguments:&dic]) {

        NSFetchRequest *fetchRequest = [NSFetchRequest new];

        NSEntityDescription *entity = [NSEntityDescription entityForName:@"Medic"
                                                  inManagedObjectContext: [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext];
        fetchRequest.entity = entity;
        return fetchRequest;
    } else
        return nil;
}];

Answer 1