How to display data from Core Data in WidgetKit - core-data

Question

Here is my code and I tried to list stored data from Core Data in WidgetKit its not showing at all. I already created app group and the data are showing at preview but when we add widget to home screen nothing shows up. I'm not sure the way I did is correct or not.
What is the best way to list Core Data records in WidgetKit?
import WidgetKit
import SwiftUI
import CoreData
// MARK: For Core Data
public extension URL {
/// Returns a URL for the given app group and database pointing to the sqlite database.
static func storeURL(for appGroup: String, databaseName: String) -> URL {
guard let fileContainer = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: appGroup) else {
fatalError("Shared file container could not be created.")
}
return fileContainer.appendingPathComponent("\(databaseName).sqlite")
}
}
var managedObjectContext: NSManagedObjectContext {
return persistentContainer.viewContext
}
var workingContext: NSManagedObjectContext {
let context = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
context.parent = managedObjectContext
return context
}
var persistentContainer: NSPersistentCloudKitContainer = {
let container = NSPersistentCloudKitContainer(name: "Countdowns")
let storeURL = URL.storeURL(for: "group.app-group-countdowns", databaseName: "Countdowns")
let description = NSPersistentStoreDescription(url: storeURL)
container.loadPersistentStores(completionHandler: { storeDescription, error in
if let error = error as NSError? {
print(error)
}
})
container.viewContext.automaticallyMergesChangesFromParent = true
container.viewContext.mergePolicy = NSMergeByPropertyStoreTrumpMergePolicy
return container
}()
// MARK: For Widget
struct Provider: TimelineProvider {
var moc = managedObjectContext
init(context : NSManagedObjectContext) {
self.moc = context
}
func placeholder(in context: Context) -> SimpleEntry {
return SimpleEntry(date: Date())
}
func getSnapshot(in context: Context, completion: #escaping (SimpleEntry) -> ()) {
let entry = SimpleEntry(date: Date())
return completion(entry)
}
func getTimeline(in context: Context, completion: #escaping (Timeline<Entry>) -> ()) {
var entries: [SimpleEntry] = []
let currentDate = Date()
let entryDate = Calendar.current.date(byAdding: .minute, value: 1, to: currentDate)!
let entry = SimpleEntry(date: entryDate)
entries.append(entry)
let timeline = Timeline(entries: entries, policy: .atEnd)
completion(timeline)
}
}
struct SimpleEntry: TimelineEntry {
let date: Date
}
struct CountdownsWidgetEntryView : View {
var entry: Provider.Entry
#FetchRequest(entity: Countdown.entity(), sortDescriptors: []) var countdowns: FetchedResults<Countdown>
var body: some View {
return (
VStack {
ForEach(countdowns, id: \.self) { (memoryItem: Countdown) in
Text(memoryItem.title ?? "Default title")
}.environment(\.managedObjectContext, managedObjectContext)
Text(entry.date, style: .time)
}
)
}
}
#main
struct CountdownsWidget: Widget {
let kind: String = "CountdownsWidget"
var body: some WidgetConfiguration {
StaticConfiguration(kind: kind, provider: Provider(context: managedObjectContext)) { entry in
CountdownsWidgetEntryView(entry: entry)
.environment(\.managedObjectContext, managedObjectContext)
}
.configurationDisplayName("My Widget")
.description("This is an example widget.")
}
}
struct CountdownsWidget_Previews: PreviewProvider {
static var previews: some View {
CountdownsWidgetEntryView(entry: SimpleEntry(date: Date()))
.previewContext(WidgetPreviewContext(family: .systemSmall))
}
}

Answer 1

Just call execute on the managed object context & since you are using a private context, make sure you call performBlock.
NSManagedObjectContext* moc = [self getManagedObjectContext];
[moc performBlock:^{
NSString *entityName = #"myEntity";
NSFetchRequest *fRequest = [[NSFetchRequest alloc]initWithEntityName:entityName];
NSPredicate *predicate = [NSPredicate predicateWithFormat: #"SELECT * FROM myEntity"];
[fRequest setPredicate:predicate];
NSError *error = nil;
NSArray *results = [moc executeFetchRequest:fRequest error:&error];
}];