Close and Re-open or refresh downloaded database - ios

Question

I'm looking for a easy solution to close my database et re-open it.
My App is using an database (CoreData) with formulas, then, when new formulas are available, my App, will download the full database and replace the actual.
This part is working well. But, once downloaded, I'd like to refresh a TableView with the new Database. I checked on the website and internet but, I didn't find answer.
Seems this is linked to the Persistent but not sure.
So I tried to reset my context but, my TableView is only updated once App been closed and re opened.
So, I'd like to know if you have time to give me an example of how to refresh or even close and re open the database.
Thanks in advance for your support.
NSData *fetchedData = [NSData dataWithContentsOfURL:[NSURL URLWithString:#"u189496386:xxxxx#xxxxx.com:21/DataBase.sqlite"]];
NSUInteger length = [fetchedData length];
ProgressDownload.progress = 0.5f;
if(length < 1)
{
ContactServer.text = #"Error downloading DataBase or Network access, please check your connection";
}
else
{
ContactServer.text = #"Server contacted, download in progress";
}
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString *filePath = [documentsPath stringByAppendingPathComponent:#"DataBase.sqlite"];
testEcriture = [fetchedData writeToFile:filePath atomically:YES];
if(testEcriture == YES)
{
ContactServer.text = #"Database updated";
ProgressDownload.progress = 1.0f;
}
Then, once back to the first view, the )viewDidLoad is executed, but it seems the content didn't changed.
mesProduits = [[NSMutableArray alloc] init];
NSEntityDescription *entityDesc = [NSEntityDescription entityForName:#"Projector" inManagedObjectContext:context];
NSFetchRequest *frequest = [[NSFetchRequest alloc] init];
[frequest setEntity:entityDesc];
NSSortDescriptor *sortDescription = [[NSSortDescriptor alloc] initWithKey:#"model" ascending:YES];
[frequest setSortDescriptors:#[sortDescription]];
NSError *error;
NSArray *matchingData = [context executeFetchRequest:frequest error:&error];

Answer 1

Your managed object context has a property, persistentStoreCoordinator, which provides a reference to the persistent store coordinator underpinning the database. The PSC accesses the persistent store to read and write the data.
So, to replace the database you would do something along these lines:
NSManagedObjectContext *context = self.context;
NSError *error = nil;
// Save the context before doing anything else.
if (![context save:&error]) {
NSLog(#"Error saving context: %#, %#", error, [error userInfo]);
abort();
}
// Get URL to the current database...
NSPersistentStoreCoordinator *psc = context.persistentStoreCoordinator;
NSPersistentStore *currentStore = psc.persistentStores[0];
NSURL *currentURL = currentStore.URL;
// Get URL to the new database...
NSURL *appDocs = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
NSURL *newDatabaseURL = [appDocs URLByAppendingPathComponent:#"DataBase.sqlite"];
// Disconnect from the current database...
if (![psc removePersistentStore:currentStore error:&error]) {
NSLog(#"Error removing store: %#, %#", error, [error userInfo]);
abort();
}
// Replace the old database with the new, keeping a backup copy...
if (![[NSFileManager defaultManager] replaceItemAtURL:currentURL withItemAtURL:newDatabaseURL backupItemName:#"DataBase.backup" options:(NSFileManagerItemReplacementUsingNewMetadataOnly | NSFileManagerItemReplacementWithoutDeletingBackupItem) resultingItemURL:nil error:&error]) {
NSLog(#"Error replacing the store: %#, %#", error, [error userInfo]);
abort();
}
// Open the new database...
NSString *failureReason = #"There was an error creating or loading the application's saved data.";
if (![psc addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:currentURL options:nil error:&error]) {
// Report any error we got.
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[NSLocalizedDescriptionKey] = #"Failed to initialize the application's saved data";
dict[NSLocalizedFailureReasonErrorKey] = failureReason;
dict[NSUnderlyingErrorKey] = error;
error = [NSError errorWithDomain:#"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
The various error cases should be properly handled, I've just logged and aborted for demonstration purposes. Be aware that your new database must match the schema for the existing database, or you will get an error. And obviously anything previously written to your old database is lost.