ios - RestKit saveToPersistentStore 不起作用

Question

我正在使用 RestKit 来实现我的休息。我从服务器获取数据并在收到数据后调用 saveToPersistentStore 这也成功了，但是当我关闭互联网并再次加载该页面时，它没有在商店中找到任何数据。

这是初始化流程-

NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"Storage" ofType:@"momd"]];
// NOTE: Due to an iOS 5 bug, the managed object model returned is immutable.
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];

// Initialize the Core Data stack
[managedObjectStore createPersistentStoreCoordinator];

NSPersistentStore __unused *persistentStore = [managedObjectStore addInMemoryPersistentStore:&error];
NSAssert(persistentStore, @"Failed to add persistent store: %@", error);

[managedObjectStore createManagedObjectContexts];

// Set the default store shared instance
[RKManagedObjectStore setDefaultStore:managedObjectStore];

我对每件事都使用 mainQueue -

    controller.managedObjectContext = managedObjectStore.mainQueueManagedObjectContext;

这是执行获取的函数:

[CMLRKSharedManager getNewsForUser:userProfile
                             urlParams:dict
                               success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
       [self.tableView reloadData];
       NSLog(@"Fetched object count %lu %@ %@", (unsigned long)self.fetchedResultsController.fetchedObjects.count , self.fetchedResultsController, self.fetchedResultsController.managedObjectContext);
       NSManagedObjectContext *managedObjCtx = [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext;

       NSError *executeError = nil;
       if(![managedObjCtx saveToPersistentStore:&executeError]) {
           NSLog(@"Failed to save to data store");
        }
       else
           NSLog(@"SAVE SUCCESSFUL");
    } failure:^(RKObjectRequestOperation *operation, NSError *error) {
        [self.tableView reloadData];
    }];
}

输出:

2014-04-02 22:24:01.547 Fetched object count 4

2014-04-02 22:24:01.555 SAVE SUCCESSFUL

现在我终止应用程序，关闭 wifi 并再次启动应用程序。该表现在是空白的，我看到 fetchResultsController 在控制台日志中看到 0 个项目

Apr 2 22:24:36 : In numberOfRows Fetched object count 0

我不知道为什么...

@wain 我更新代码如下 -

NSError *error = nil;
NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"Cover" ofType:@"momd"]];
// NOTE: Due to an iOS 5 bug, the managed object model returned is immutable.
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];

// Initialize the Core Data stack
[managedObjectStore createPersistentStoreCoordinator];

评论了这两行

//    NSPersistentStore __unused *persistentStore = [managedObjectStore addInMemoryPersistentStore:&error];
//    NSAssert(persistentStore, @"Failed to add persistent store: %@", error);
//    

而是添加了 sqlite 数据库，但现在应用程序崩溃了

BOOL success = RKEnsureDirectoryExistsAtPath(RKApplicationDataDirectory(), &error);
if (! success) {
    RKLogError(@"Failed to create Application Data Directory at path '%@': %@", RKApplicationDataDirectory(), error);
}
NSString *path = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"Store.sqlite"];
NSPersistentStore *persistentStore = [managedObjectStore addSQLitePersistentStoreAtPath:path fromSeedDatabaseAtPath:nil withConfiguration:nil options:nil error:&error];
if (! persistentStore) {
    RKLogError(@"Failed adding persistent store at path '%@': %@", path, error);
}

Answer 1

根据您的描述，问题是您只有一个内存存储:

[managedObjectStore addInMemoryPersistentStore:&error];

所以没有任何东西被保存到磁盘。您应该更改此设置以便使用 SQLite 存储。这会将数据保存到磁盘，并且通常在大多数使用场景中都能更好地工作。