core-data – Page 6 – Tarik Billa

Can I apply multiple predicates to an NSFetchRequest? Would it be better to manually parse my results?

August 27, 2023 by Tarik

Yes it’s possible. You’re looking for compound predicates and here’s an example with AND predicates: NSPredicate *compoundPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray of Predicates]]; You can also use notPredicateWithSubpredicates and orPredicateWithSubpredicates depending on your needs. Link to documentation https://developer.apple.com/documentation/foundation/nscompoundpredicate

How come I can cast to NSManagedObject but not to my entity’s type?

August 27, 2023 by Tarik

Make sure your Class name field is actually Module.Task, where Module is the name of your app. CoreData classes in Swift are namespaced. Right now, your object is being pulled out of the context as an NSManagedObject, not as a Task, so the as-cast is failing.

Deleting all data in a Core Data entity in Swift 3

August 26, 2023 by Tarik

You’re thinking of NSBatchDeleteRequest, which was added in iOS 9. Create one like this: let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: “Employee”) let request = NSBatchDeleteRequest(fetchRequest: fetch) You can also add a predicate if you only wanted to delete instances that match the predicate. To run the request: let result = try managedObjectContext.executeRequest(request) Note that batch requests don’t … Read more

Crash when adding persistent store (iCloud enabled) in app delegate

August 25, 2023 by Tarik

Updated answer to resync your devices Months of tinkering around have led me to figuring out what (I believe) the rooted problem is. The issue has been getting devices to once again talk to each other after they fall out of sync. I can’t say for sure what causes this, but my suspicion is that … Read more

How to access CoreData model in today extension (iOS)

August 22, 2023 by Tarik

What you really want is to access your persistent store (most likely a SQLite database). In order to achieve that, you need to configure App Groups and make sure that your host app configures the Core Data stack using your shared container (so your store is accessible in extension as well). Something like: NSString *containerPath … Read more

How can I find out if the iPhone user currently has a passcode set and encryption enabled?

August 17, 2023 by Tarik

Disclaimer: This answer was valid until ios 4.3.3 If data protection is turned on, a newly created file will have a nil NSFileProtectionKey by default. If data protection is turned off, a newly created file will have a NSFileProtectionNone NSFileProtectionKey by default. Thus, you could detect the presence of file protection with the following code: … Read more

Is it possible to override getters and setters for @dynamic properties in an NSManagedObject subclass?

August 14, 2023 by Tarik

Never call [super valueForKey:..] in a NSManagedObject subclass! (unless you implemented them in a superclass yourself) Instead use the primitive accessor methods. Sample getter/setter implementation from ADC: @interface Department : NSManagedObject @property(nonatomic, strong) NSString *name; @end @interface Department (PrimitiveAccessors) – (NSString *)primitiveName; – (void)setPrimitiveName:(NSString *)newName; @end @implementation Department @dynamic name; – (NSString *)name { [self … Read more

Core data, how to get NSManagedObject’s ObjectId when NSFetchRequest returns NSDictionaryResultType?

August 13, 2023 by Tarik

Yes you can, using the very nifty but badly-documented NSExpressionDescription class. You need to add a properly-configured NSExpressionDescription object to the array of NSPropertyDescription objects you set via setPropertiesToFetch: for your NSFetchRequest. For example: NSExpressionDescription* objectIdDesc = [[NSExpressionDescription new] autorelease]; objectIdDesc.name = @”objectID”; objectIdDesc.expression = [NSExpression expressionForEvaluatedObject]; objectIdDesc.expressionResultType = NSObjectIDAttributeType; myFetchRequest.propertiesToFetch = [NSArray arrayWithObjects:objectIdDesc, anotherPropertyDesc, … Read more

How to use the first character as a section name

August 12, 2023 by Tarik

You should just pass “name” as the sectionNameKeyPath. See this answer to the question “Core Data backed UITableView with indexing”. UPDATE That solution only works if you only care about having the fast index title scroller. In that case, you would NOT display the section headers. See below for sample code. Otherwise, I agree with … Read more

SwiftUI View and @FetchRequest predicate with variable that can change

August 12, 2023 by Tarik

had the same problem, and a comment of Brad Dillon showed the solution: var predicate:String var wordsRequest : FetchRequest<Word> var words : FetchedResults<Word>{wordsRequest.wrappedValue} init(predicate:String){ self.predicate = predicate self.wordsRequest = FetchRequest(entity: Word.entity(), sortDescriptors: [], predicate: NSPredicate(format: “%K == %@”, #keyPath(Word.character),predicate)) } in this example, you can modify the predicate in the initializer.