问题
I am learning Swift from Online Course and while my instructor integrating CoreData to her existing code, She creates a new core data model and copy-paste App Delegate. But in her DataModel, there is not a SceneDelegate while there is in mine.
The problem is that I can not do the same things as her because of these differences. Therefore, I copied SceneDelegate.swift file into my Xcode project and copy other things from DataModel App Delegate.
After this solution, I got a black screen.
I do not know I should add her and my app delegate or not but differences are while I do not have applicationWillResignActive, applicationDidEnterBackgraound, etc. in the Core Data Model App Delegate, she does have.
How can I integrate CoreData into my project while there are these differences?
Thanks!
this is my app delegate file
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
return true
}
func applicationWillResignActive(_ application: UIApplication) {
}
func applicationDidEnterBackground(_ application: UIApplication) {
}
func applicationWillEnterForeground(_ application: UIApplication) {
}
func applicationDidBecomeActive(_ application: UIApplication) {
}
func applicationWillTerminate(_ application: UIApplication) {
}
}
回答1:
You need these lines of code:
// MARK: - Core Data stack
lazy var persistentContainer: NSPersistentContainer = {
/*
The persistent container for the application. This implementation
creates and returns a container, having loaded the store for the
application to it. This property is optional since there are legitimate
error conditions that could cause the creation of the store to fail.
*/
let container = NSPersistentContainer(name: "TestCoreData")
container.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error as NSError? {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
/*
Typical reasons for an error here include:
* The parent directory does not exist, cannot be created, or disallows writing.
* The persistent store is not accessible, due to permissions or data protection when the device is locked.
* The device is out of space.
* The store could not be migrated to the current model version.
Check the error message to determine what the actual problem was.
*/
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
return container
}()
// MARK: - Core Data Saving support
func saveContext () {
let context = persistentContainer.viewContext
if context.hasChanges {
do {
try context.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
}
Put it after the applicationWillTerminate function but within the AppDelegate class.
The code is automatically added when creating an Xcode project and checking the 'Use Core Data' checkbox. You can always create a new Xcode project, check the 'Use Core Data' checkbox and then copy and paste the code near the end of the AppDelegate which was automatically created.
来源：https://stackoverflow.com/questions/60128296/getting-black-screen-while-integrating-coredata-to-my-todo-app-swift