I finally got around to trying out the new query generations in iOS 10 but when I turned it on, I started getting exceptions when calling mergeChanges(fromContextDidSave:). My app supports iOS 9 as well so I can't use NSPersistentContainer quit yet. Here's where I am setting up the Core Data stack: (also at https://gist.github.com/davbeck/85adfe8ab723562abf7c998e53f8e9f5) / static func defaultStoreURL() -> URL? { do { guard var url = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: appGroupIdentifier) else { return nil } url.appendPathComponent("EngagementData") try FileManager.default.createDirectory(at: url, withIntermediateDirectories: true) url.appendPathComponent("Data.sqlite3") return url } catch { return nil } } public let storeURL: URL? public let managedObjectModel: NSManagedObjectModel = { let momURL = Bundle(for: APIClient.self).url(forResource: "Realm", withExtension: "momd")! return NSManagedObjectModel(contentsOf: momURL)! }() fileprivate(set) open lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = { let persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel) let options = [ NSMigratePersistentStoresAutomaticallyOption: true, NSInferMappingModelAutomaticallyOption: true, ] if let storeURL = self.storeURL { do { self.logger.info("storeURL: \(self.storeURL)") try persistentStoreCoordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: self.storeURL, options: options) return persistentStoreCoordinator } catch let error { self.logger.error("Could not create NSPersistentStoreCoordinator", error: error) } } / try! persistentStoreCoordinator.addPersistentStore(ofType: NSInMemoryStoreType, configurationName: nil, at: nil, options: nil) return persistentStoreCoordinator }() fileprivate(set) public lazy var backgroundContext: NSManagedObjectContext = { let context = ManagedObjectContext(concurrencyType: .privateQueueConcurrencyType) context.persistentStoreCoordinator = self.persistentStoreCoordinator context.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy context.dispatchGroup = self.dispatchGroup context.shouldDeleteInaccessibleFaults = true if #available(iOS 10, *) { do { try context.setQueryGenerationFrom(.current) } catch { self.logger.error("could not activate query generation", error: error) } } return context }() public func performBackgroundTask(_ block: @escaping (NSManagedObjectContext) -> Void) { self.backgroundContext.perform { block(self.backgroundContext) } } fileprivate(set) public lazy var viewContext: NSManagedObjectContext = { let context = ManagedObjectContext(concurrencyType: .mainQueueConcurrencyType) context.persistentStoreCoordinator = self.persistentStoreCoordinator context.mergePolicy = NSMergeByPropertyStoreTrumpMergePolicy context.dispatchGroup = self.dispatchGroup context.shouldDeleteInaccessibleFaults = true if #available(iOS 10, *) { do { try context.setQueryGenerationFrom(.current) } catch { self.logger.error("could not activate query generation", error: error) } } return context }() / func viewContextDidSave(_ notification: Notification) { self.logger.debug("viewContextDidSave: \(notification.userInfo)") self.backgroundContext.perform { self.backgroundContext.mergeChanges(fromContextDidSave: notification) } } func backgroundContextDidSave(_ notification: Notification) { self.logger.debug("backgroundContextDidSave: \(notification.userInfo)") self.viewContext.perform { self.viewContext.mergeChanges(fromContextDidSave: notification) } }Inside of backgroundContextDidSave, self.viewContext.mergeChanges(fromContextDidSave: notification) causes an EXC_BAD_INSTRUCTION and prints out "More code needs to be written". Am I missing something? What other code needs to be written?!?!

I'm experimenting with replacing my graph implementation with SwiftCharts. One issue I ran into is that I'm graphing stock data, but that data is only present during trading hours. In the screenshot I included, you can see my implementation on top vs the SwiftCharts version as well as the stocks app. Because trading is from 9:30AM-4:00PM, if the times are graphed linearly, there will be large gaps for nights and weekends. The way I implemented this before was to treat each "tick" of data as equal width. .chartXScale(type: .category) seems like it would do something similar, but if I try that I get the following error: Fatal error: the specified scale type is incompatible with the data values and visual property.

How can you set a manual range on a chart? There is .chartXScale(range:) but the only options seem to be to add padding to the values in the chart. I need to have a specific start and end date.

In the contacts app there are contacts included that include "Siri found in Mail". I have an app that includes a directory of contact information. Is it possible to include contacts found in my app to the system?

The documentation states that you can use either finishDeferredLightweightMigrationTask or finishDeferredLightweightMigration to complete a deferred migration at a later time. However when I tried finishDeferredLightweightMigrationTask, I noticed that the metadata for the store isn't updated. How would you know when the migration has completed and you can stop calling finishDeferredLightweightMigrationTask? The reason I was reaching for the individual migration task approach is that I thought it would be better for handling an expired background task since I could check for cancellation after each step.