core-data

问题 I am trying to delete a single element of the coreData set using a button inside a collectionviewcell. So the cell has a label with the result of the core data fetch. When I hit the button it should delete the cell making it no longer appear. Also the the core data single set item should be perementley deleted. I have scence this used before in protocols but not using core data.The core data is var itemName. class CustomCell: UICollectionViewCell { @objc func delete() { }} class

问题 I am trying to delete a single element of the coreData set using a button inside a collectionviewcell. So the cell has a label with the result of the core data fetch. When I hit the button it should delete the cell making it no longer appear. Also the the core data single set item should be perementley deleted. I have scence this used before in protocols but not using core data.The core data is var itemName. class CustomCell: UICollectionViewCell { @objc func delete() { }} class

问题 I have an entity which looks like this: Entityname = Country with the attributes "city" and "person". Country *country = [NSEntityDescription insertNewObjectForEntityForName:@"Country" inManagedObjectContext:context]; country.city = @"New York"; country.person = @"Doug"; country.person = @"Carry"; country.person = @"Arthur"; I want to save more then one people in that City . I am using the code posted above, but only the last person is saved. How I can save more then one people in CoreData ?

问题 I want to achieve the following: Whenever someone triggers a CoreData save (ie. NSManagedObjectContextDidSave notification gets sent), I'd like to perform some background calculation based the changed NSManagedObject. Concrete example: Assume in a notes app, I want to asynchronously calculate the total number of words in all notes. The problem currently lies with the fact that NSManagedObject context is explicitly bound to thread and you are discouraged from using NSManagedObject s outside

问题 I want to achieve the following: Whenever someone triggers a CoreData save (ie. NSManagedObjectContextDidSave notification gets sent), I'd like to perform some background calculation based the changed NSManagedObject. Concrete example: Assume in a notes app, I want to asynchronously calculate the total number of words in all notes. The problem currently lies with the fact that NSManagedObject context is explicitly bound to thread and you are discouraged from using NSManagedObject s outside

问题 I want to achieve the following: Whenever someone triggers a CoreData save (ie. NSManagedObjectContextDidSave notification gets sent), I'd like to perform some background calculation based the changed NSManagedObject. Concrete example: Assume in a notes app, I want to asynchronously calculate the total number of words in all notes. The problem currently lies with the fact that NSManagedObject context is explicitly bound to thread and you are discouraged from using NSManagedObject s outside

问题 I'm working on a iOS/macOS project where I'm using CoreData. It works fine, but it outputs enormous amounts of debugging info to the Console. This makes the Console unusable, since my print statements are buried in all the CoreData related stuff. I have a pretty simple CoreData setup with fetching of some data, so these are not errors, just general event logs it seems. I have the same results on other projects I have used CoreData. Any way to reduce/remove this logging to the console? Some

问题 Apple introduced the NSPersistentCloudKitContainer with iOS13 which enable us to use CloudKit with Core Data. I got it working pretty much instantly on different devices but my main issue is still left. Is it possible to share the data in an easy way with other users? I've been reading on CKShare but don't see how I can go from NSPersistentCloudKitContainer to that in an easy way. 回答1: There are methods on NSPersistentCloudKitContainer for accessing the underlying cloudkit records: https:/

问题 Swift allows you to define enum but core data doesn't support (out of the box) how to save them. The recommended solution I have seen on the internet (and used thus far) is to use a private variable: class ManagedObjectSubClass : NSManagedObject { enum Cards : Int { case Diamonds, Hearts } @nsmanaged var cardRaw: Int var card : Cards { set { self.cardRaw = newValue.rawValue } get { return Cards(RawValue:cardRaw)! } } } An alternate solution is given in the answer below. 回答1: Another approach

问题 When I created an iOS 11 app using the core data template, it auto generated the following code in AppDelete.m. synthesize persistentContainer = _persistentContainer; - (NSPersistentContainer *)persistentContainer { // The persistent container for the application. This implementation creates and returns a container, having loaded the store for the application to it. @synchronized (self) { if (_persistentContainer == nil) { _persistentContainer = [[NSPersistentContainer alloc] initWithName:@