ios - 如何使用 swift 3 为核心数据生成虚拟数据

Question

我创建了一个支持 iOS 8.0 及以上版本的项目。所以我稍微更改了 AppDelegate 中的代码。

应用委托(delegate)

// MARK: - Core Data stack

    @available(iOS 10.0, *)
    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: "coreDataTestForPreOS")
        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
    }()
    
    // iOS 9 and below
    lazy var applicationDocumentsDirectory: URL = {
        
        let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        return urls[urls.count-1]
    }()
    
    lazy var managedObjectModel: NSManagedObjectModel = {
        // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
        let modelURL = Bundle.main.url(forResource: "coreDataTestForPreOS", withExtension: "momd")!
        return NSManagedObjectModel(contentsOf: modelURL)!
    }()
    
    lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
        // The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added 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.
        // Create the coordinator and store
        let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
        let url = self.applicationDocumentsDirectory.appendingPathComponent("SingleViewCoreData.sqlite")
        var failureReason = "There was an error creating or loading the application's saved data."
        do {
            try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
        } catch {
            // Report any error we got.
            var dict = [String: AnyObject]()
            dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
            dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?
            
            dict[NSUnderlyingErrorKey] = error as NSError
            let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
            // Replace this with code to handle the error appropriately.
            // abort() 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.
            NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
            abort()
        }
        
        return coordinator
    }()
    
    lazy var managedObjectContext: NSManagedObjectContext = {
        // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
        let coordinator = self.persistentStoreCoordinator
        var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
        managedObjectContext.persistentStoreCoordinator = coordinator
        return managedObjectContext
    }()

    // MARK: - Core Data Saving support
    
    func saveContext () {
    
        if #available(iOS 10.0, *) {
            
            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)")
                }
                
        } else {
            // iOS 9.0 and below - however you were previously handling it
                if managedObjectContext.hasChanges {
                    do {
                        try managedObjectContext.save()
                    } catch {
                        // Replace this implementation with code to handle the error appropriately.
                        // abort() 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
                        NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
                        abort()
                    }
                }
            
            }
        }
    }

}

let ad = UIApplication.shared.delegate as! AppDelegate

@available(iOS 10.0, *)
let contextAbove = ad.persistentContainer.viewContext

let contextBelow = ad.managedObjectContext

现在我想生成数据到数据库。我对其使用自定义函数。

函数

func generateData() {
        
            if #available(iOS 10.0, *) {
                let item1 = Item(context: contextAbove)
                item1.name = "Alwin"
            } else {
                // Fallback on earlier versions
                
            }
        
        // to save data
        ad.saveContext()
    }

以上代码未完成，请帮我完成。
在 iOS 10 中，我使用以下函数来实现这一点

func generateData() {
        
        let item1 = Item(context: contextAbove)
        item1.name = "Alwin"
        
        // to save data
        ad.saveContext()
    }

Answer 1

您可以使用如下代码

func generateData() {

        if #available(iOS 10.0, *) {
            let item1 = Item(context: contextAbove)
            item1.name = "Alwin"
        } else {
            // Fallback on earlier versions
            let managedObjectContext = contextBelow
            let entityDesc = NSEntityDescription.entity(forEntityName: "Item", in: managedObjectContext)
            let item1 = Item(entity: entityDesc!, insertInto: managedObjectContext)
            item1.name = "Alwin"
        }

        // to save data
        ad.saveContext()
}