how to update core data entered values

问题

[newVehicle setValue: _txtFieldVehicleNumber.text forKey:@"number"];

[newVehicle setValue: lblFuelType.text forKey:@"fueltype"];

[newVehicle setValue: lblFuelUnit.text forKey:@"fuelunit"];

[newVehicle setValue: lblDistanceUnit.text forKey:@"distanceunit"];

I want to update my core data entity named "Vehicle", for that entity I have several attributes and I want to update some of them but not all when I select particular attribute from the entity. So what should I do ??

回答1:

you can do the following (approximate code. Implement error handling and check syntax).

NSFetchRequest *fetchRequest=[NSFetchRequest fetchRequestWithEntityName:@"Vehicle"];
NSPredicate *predicate=[NSPredicate predicateWithFormat:@"vehicle_id==%@",vehicle_id]; // If required to fetch specific vehicle
fetchRequest.predicate=predicate;
Vehicle *newVehicle=[[self.managedObjectContext executeFetchRequest:fetchRequest error:nil] lastObject];

[newVehicle setValue: _txtFieldVehicleNumber.text forKey:@"number"];

[newVehicle setValue: lblFuelType.text forKey:@"fueltype"];

[newVehicle setValue: lblFuelUnit.text forKey:@"fuelunit"];

[newVehicle setValue: lblDistanceUnit.text forKey:@"distanceunit"];

[self.managedObjectContext save:nil]

回答2:

Get an entity from core data:

VVdAppDelegate *delegate = (VVdAppDelegate *)[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *managedObjectContext = [delegate managedObjectContext];
NSEntityDescription *entityDescriptionDelegate = [NSEntityDescription entityForName:@"entityName" inManagedObjectContext:managedObjectContext];
NSFetchRequest *requestData = [[NSFetchRequest alloc] init];
[requestData setEntity:entityDescriptionDelegate];
NSError *error;

If there are more than an NSManagedObject

NSArray *objectsArray = [managedObjectContext executeFetchRequest:requestData error:&error];

for (NSManagedObject *object in objectsArray) {

        // Here update values of every object

}

// And save values to core data
[managedObjectContext save:&error];

来源：https://stackoverflow.com/questions/19053117/how-to-update-core-data-entered-values

标签

ios

core-data

attributes

entity

insert-update