Question

我正在尝试将Core Data添加到支持iOS 9 +的现有项目中。

我添加了Xcode生成的代码：

// MARK: - Core Data stack

    lazy var persistentContainer: NSPersistentContainer = {

        let container = NSPersistentContainer(name: "tempProjectForCoreData")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {

                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 {
                let nserror = error as NSError
                fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
            }
        }
    }

在Xcode中生成标准CoreData堆栈后，我发现新的NSPersistentContainer类可以从iOS 10获得，因此我收到错误。

正确的CoreData Stack应该如何支持iOS 9和10？

Answer 1

这是适用于我的核心数据堆栈。我认为为了支持iOS 10，我需要实现NSPersistentContainer类，但我发现带有NSPersistentStoreCoordinator的旧版本也可以。

您必须更改模型（coreDataTemplate）和项目（SingleViewCoreData）的名称。

Swift 3 ：

// MARK: - CoreData Stack

    lazy var applicationDocumentsDirectory: URL = {
        // The directory the application uses to store the Core Data store file. This code uses a directory named "com.cadiridris.coreDataTemplate" in the application's documents Application Support directory.
        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: "coreDataTemplate", 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
        managedObjectContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
        return managedObjectContext
    }()

    // MARK: - Core Data Saving support

    func saveContext () {
        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()
            }
        }
    }

Answer 2

使用下一个Struct for ios 9和10

这是上下文使用nex并将ModelCoreData替换为CoreData的Model名称 Storage.share.context

导入基金会导入CoreData

/// NSPersistentStoreCoordinator扩展扩展NSPersistentStoreCoordinator {

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}

struct Storage {

/// NSPersistentStoreCoordinator error types
public enum CoordinatorError: Error {
    /// .momd file not found
    case modelFileNotFound
    /// NSManagedObjectModel creation fail
    case modelCreationError
    /// Gettings document directory fail
    case storePathNotFound
}

/// Return NSPersistentStoreCoordinator object
static func coordinator(name: String) throws -> NSPersistentStoreCoordinator? {

    guard let modelURL = Bundle.main.url(forResource: name, withExtension: "momd") else {
        throw CoordinatorError.modelFileNotFound
    }

    guard let model = NSManagedObjectModel(contentsOf: modelURL) else {
        throw CoordinatorError.modelCreationError
    }

    let coordinator = NSPersistentStoreCoordinator(managedObjectModel: model)

    guard let documents = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).last else {
        throw CoordinatorError.storePathNotFound
    }

    do {
        let url = documents.appendingPathComponent("\(name).sqlite")
        let options = [ NSMigratePersistentStoresAutomaticallyOption : true,
                        NSInferMappingModelAutomaticallyOption : true ]
        try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: options)
    } catch {
        throw error
    }

    return coordinator
}

}

适用于Swift中iOS 9和iOS 10的CoreData Stack

2 个答案: