CoreData delete multiple objects

Question

I know how to delete a single object in CoreData I\'m just wondering if theres a simpler way of deleting multiple objects?

For single delete you can use

Answer 1

iOS10 & Swift 3

    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "EntityName")
    let deleteRequest = NSBatchDeleteRequest( fetchRequest: fetchRequest)

    do{
        try mContext.execute(deleteRequest)
    }catch let error as NSError {//handle error here }

This deletes all the objects of EntityName but you can apply additional filtering with NSPredicate

Answer 2

No, there is no specific method to remove multiple objects atm. But I would do something like this, simillar to what you already are doing:

- (void)removeFromManagedObjectContext {
  NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    fetchRequest.entity = [NSEntityDescription entityForName:@"YourEntity" inManagedObjectContext:managedObjectContext];

    NSArray *results = [managedObjectContext executeFetchRequest:fetchRequest error:nil];

 
  
    for (Your Entity *Entity in results) {
        [managedObjectContext deleteObject:Entity];
    }
}

Answer 3

iOS 9

Swift

let fetchRequest = NSFetchRequest(entityName: "EntityName") let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)

do {
    try myPersistentStoreCoordinator.executeRequest(deleteRequest, withContext: myContext) } catch let error as NSError {
    // TODO: handle the error 
}

Objective-C

NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"EntityName"];
NSBatchDeleteRequest *deleteRq = [[NSBatchDeleteRequest alloc] initWithFetchRequest:request];

NSError *deleteError = nil;
[myPersistentStoreCoordinator executeRequest:deleteRq withContext:myContext error:&deleteError];

iOS 8 and older

NSFetchRequest *fr = [[NSFetchRequest alloc] init];
[fr setEntity:[NSEntityDescription entityForName:@"EntityName" inManagedObjectContext:myContext]];
[fr setIncludesPropertyValues:NO]; //only fetch the managedObjectID

NSError *error = nil;
NSArray *objects = [myContext executeFetchRequest:fr error:&error];

//error handling goes here
for (NSManagedObject *object in objects) {
  [myContext deleteObject:object];
}
NSError *saveError = nil;
[myContext save:&saveError];
//more error handling here

Answer 4

As I know, there isn't a method for that... You should do like you're already doing. There is a method called deletedObjects but it just returns the set of objects that will be removed from their persistent store during the next save operation, as described in class reference.

Answer 5

From https://www.avanderlee.com/swift/nsbatchdeleterequest-core-data/

extension NSManagedObjectContext {
    
    /// Executes the given `NSBatchDeleteRequest` and directly merges the changes to bring the given managed object context up to date.
    ///
    /// - Parameter batchDeleteRequest: The `NSBatchDeleteRequest` to execute.
    /// - Throws: An error if anything went wrong executing the batch deletion.
    public func executeAndMergeChanges(using batchDeleteRequest: NSBatchDeleteRequest) throws {
        batchDeleteRequest.resultType = .resultTypeObjectIDs
        let result = try execute(batchDeleteRequest) as? NSBatchDeleteResult
        let changes: [AnyHashable: Any] = [NSDeletedObjectsKey: result?.result as? [NSManagedObjectID] ?? []]
        NSManagedObjectContext.mergeChanges(fromRemoteContextSave: changes, into: [self])
    }
}

My goal is to delete some objects so here's how I use it

var objectsToRemove = [NSManagedObjectID]()
// gather objectIDs

let batchDeleteRequest = NSBatchDeleteRequest(objectIDs: objectsToRemove)
do {
    try defaultContext.executeAndMergeChanges(using: batchDeleteRequest)            
} catch {
    // handle error
}