Save data with Magical Record inside a block - core-data

Question

I am retrieving some data from an API resource and I want to store the result inside my City entity using Magical Record and when the process finish, reload a tableView in my ViewController with the results.
All is fine but when I start the app for the first time,dowload process is started and the data is saved in core data.
but the table view in my ViewControllers is empty.
If I launch the app after the first time
the tableView refresh correctly.
I don't know if the problem is in threads... Can anybody help me?
ViewController :
Here I start the request. When block is called, I store cities array and reload tableView
- (void)getCitiesFromDataStore {
[[APIManager sharedManager] getCitiesWithCompletion:^(NSArray *cities) {
_dataSourceArray = cities;
[self.citiesTableView reloadData];
} failure:^(NSError *error) {
NSLog(#"%#",error.localizedDescription);
}];
}
APIMAnager
- (void)getCitiesWithCompletion:(void (^)(NSArray *))succesBlock
failure:(void (^)(NSError *))errorBlock
{
NSArray *cachedCities = [City findAllCities];
if ([cachedCities count] == 0) {
[self GET:#"cities" parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
NSArray *results = responseObject[#"cities"];
[City MR_importFromArray:results];
[[NSManagedObjectContext MR_defaultContext] MR_saveToPersistentStoreAndWait];
NSArray *cities = [City findAllCities];
succesBlock(cities);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
errorBlock(error);
}];
return;
}
// Si ya hay ciudades almacenadas en CoreData, devuelvo el
// succesblock con las ciudades de CoreData
succesBlock(cachedCities);
}
I have a Category also to manage actions with the City entity
City+DBOperations
+ (NSArray *)findAllCities
{
NSArray *cities = [City MR_findAll];
return cities;
}

Answer 1

I know you said you resolved it, but for others who might be coming here another thing you could try is wrapping the import in a saveWithBlock:completion: and do your find in the completion block.
Also make sure you know which context each method is using. It is often helpful to be explicit about that.
Therefore you could change it to (this is untested, but should give you the concept):
[self GET:#"cities" parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
NSArray *results = responseObject[#"cities"];
[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) {
[City MR_importFromArray:results inContext:localContext];
} completion:^(BOOL contextDidSave, NSError *error) {
NSArray *cities = [User MR_findAllInContext:[NSManagedObjectContext MR_defaultContext]];
succesBlock(cities);
}];
} failure:^(NSURLSessionDataTask *task, NSError *error) {
errorBlock(error);
}];