Data gets deleted after closing the app [IOS] - iphone

Question

I wrote an ios application in order to save a data to core data and then fetch it with the following code:
NSManagedObjectContext *context = [self managedObjectContext];
NSError *error;
NSManagedObject *failedBankInfo = [NSEntityDescription
insertNewObjectForEntityForName:#"UserData"
inManagedObjectContext:context];
[failedBankInfo setValue:[NSNumber numberWithInt:1] forKey:#"userId"];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"UserData" inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
for (NSManagedObject *info in fetchedObjects) {
NSLog(#"Name: %#", [info valueForKey:#"userId"]);
}
There no problem in here. But After I close my application and modify the setvalue to 2, I only receive the last data which is 2. Earlier data (1) gets deleted.
What should I do to keep the data entries even after I close my application.
Thank You!

Answer 1

You need to create a UIManagedDocument to save the Core Data information. I usually create the UIManagedDocument as a property of the class. For the example I have created a UIManagedDocument called theManagedDocument:
NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
url = [url URLByAppendingPathComponent:#"DocumentName"];
self.theManagedDocument = [[UIManagedDocument alloc] initWithFileURL:url];
if([[NSFileManager defaultManager] fileExistsAtPath:[url path]])
{
[theManagedDocument openWithCompletionHandler:^(BOOL success){
if(success) [self documentIsReady];
if(!success) NSLog(#"Couldn't Open Document");
}];
}
else
{
[theManagedDocument saveToURL:url forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success){
if(success) [self documentIsReady];
if(!success) NSLog(#"Couldn't Create Document");
}];
}
Then I create a method called documentIsReady that is called when the document has been successfully created or opened (opened if it is already present, created otherwise). I will also keep the context as a property. Here it is called context. I also added in your code:
- (void) documentIsReady
{
if(self.theManagedDocument.documentState == UIDocumentStateNormal)
{
self.context = self.theManagedDocument.managedObjectContext;
NSError *error;
NSManagedObject *failedBankInfo = [NSEntityDescription
insertNewObjectForEntityForName:#"UserData"
inManagedObjectContext:self.context];
[failedBankInfo setValue:[NSNumber numberWithInt:1] forKey:#"userId"];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"UserData" inManagedObjectContext:self.context];
[fetchRequest setEntity:entity];
NSArray *fetchedObjects = [self.context executeFetchRequest:fetchRequest error:&error];
for (NSManagedObject *info in fetchedObjects) {
NSLog(#"Name: %#", [info valueForKey:#"userId"]);
}
}
}
You will then want to close the document when you are done using:
[self.theManagedDocument closeWithCompletionHandler:^(BOOL success){
if(success) NSLog(#"Closed Successfully");
if(!success) NSLog(#"Error Closing Document");
}];

Answer 2

You did not save your new record.
[self.managedObjectContext save:nil];