Read the value of an attribute of a Core Data entity - swift

Question

I'm trying to read the value of an attribute (called 'name') of an entity (called 'List'), stored in a Core Data database. The issue that I have is that it says that the value of that attribute is nil, which should be a String.
My code for retrieving all List-entities is as follows:
container?.performBackgroundTask { [weak self] context in
self?.wordLists = try! List.all(in: context)
DispatchQueue.main.async(execute: {
print("Main queue available, reloading tableview.")
self?.wordListSelector.reloadData()
})
}
class func all(in context: NSManagedObjectContext) throws -> [List] {
let listRequest: NSFetchRequest<List> = List.fetchRequest()
do {
let list = try context.fetch(listRequest)
print(list)
return list
} catch {
print("error")
throw error
}
}
This prints:
[<__Words.List: 0x6000000937e0> (entity: List; id: 0xd00000000004000c <x-coredata://999D0158-64BD-44FD-A0B1-AB4EC03B9386/List/p1> ; data: <fault>), <__Words.List: 0x600000093a60> (entity: List; id: 0xd00000000008000c <x-coredata://999D0158-64BD-44FD-A0B1-AB4EC03B9386/List/p2> ; data: <fault>), <__Words.List: 0x600000093ab0> (entity: List; id: 0xd0000000000c000c <x-coredata://999D0158-64BD-44FD-A0B1-AB4EC03B9386/List/p3> ; data: <fault>)]
Which shows me that there should be 3 lists in the database, which is as expected.
I have created a variable like this:
var wordLists: [List] = [] {
didSet {
print("Detected wordList update, waiting for main queue.")
DispatchQueue.main.async(execute: {
print("Main queue available, reloading tableview.")
self.wordListSelector.reloadData()
})
}
}
This variable holds the List-entities that I retrieved by calling that all() function which I mentioned previously.
The following two methods will fill my TableView:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print("numberOfRowsInSection: \(wordLists.count).")
return wordLists.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cellIdentifier = "CategoryCell"
let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath)
print("cellForRowAt: \(indexPath.row) has name \(wordLists[indexPath.row].name).")
cell.textLabel?.text = wordLists[indexPath.row].name
return cell
}
This prints the following:
Detected wordList update, waiting for main queue.
Main queue available, reloading tableview.
numberOfRowsInSection: 3.
cellForRowAt: 0 has name nil.
cellForRowAt: 1 has name nil.
cellForRowAt: 2 has name nil.
Why is the name nil? Is this because the data is still 'faulted'? By viewing topics online I thought that Core Data automaticly unfaulted its data when you try to access it. What am I doing wrong?
Edit:
If I change the didset to the following:
var wordLists: [List] = [] {
didSet {
print("Wordlist was updated.")
for wordList in wordLists {
print(wordList)
print(wordList.name)
}
}
}
It does print the names (Optional("nameofitem1")). In the cellForRowAt it still prints 'nil'.

Answer 1

What you do looks like a good job for the NSFetchedResultsController. That will also help with the threading you might mix up as suggested in the comments. There is really good documentation on the NSFetchedResultsController