ios - 如何做我的 appDelegate coredata 支持 ios 9 我正在使用 xCode 8

Question

我实际上遇到了一个问题，我使用的是 Xcode 8、iOS 10，但在我的运行目标中我给了它 9.1，问题发生时我包含了 CoreData，但我需要正常工作 enter image description here iOS 9 和 iOS 10

我把图片放在这里

这部分代码

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: "delete")
    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)")
        }
    }
}

And in this part are my functions

func saveData(){

let  appDelegate = UIApplication.shared.delegate as!  AppDelegate
     if #available(iOS 10.0, *) {
       let context = appDelegate.persistentContainer.viewContext
        let newToken =       NSEntityDescription.insertNewObject(forEntityName: "Token_entity", into: context)
    newToken.setValue("85724985724897247ifeifjhadjkfhsauq89r8479138941874193874", forKey: "accessToken" )
    do
    {

        try context.save()
        print("SAVED")

    }
    catch
    {

        ///PROCESS ERROR

    }

} else {
    // Fallback on earlier versions
}
 }


  func requestCoreData (){

let appDel = UIApplication.shared.delegate as! AppDelegate
if #available(iOS 10.0, *) {
    let contex = appDel.persistentContainer.viewContext
    let requests = NSFetchRequest<NSFetchRequestResult>(entityName: "Token_entity")
    requests.returnsObjectsAsFaults = false


    do
    {

        let results  = try contex.fetch(requests)
        if results.count > 0
        {

            for result in results as! [NSManagedObject]{

                if let tokenrequest = result.value(forKey: "accessToken") as? String
                {

                    print(tokenrequest)


                }



            }


        }

    }
    catch
    {

        ///PROCESS ERROR

    }


} else {
    // Fallback on earlier versions
}

 }

Answer 1

当您创建选择该选项的项目时，iOS 9 和早期版本的 Core Data 代码默认进入应用程序委托(delegate)，其主要区别在于应用程序访问 ManagedObjectContext 的方式。在 iOS 10 中，上下文是通过一个名为 NSPercientContainer 的新单例对象访问的(请参阅下面使用 Core Data 创建的 iOS 10 项目中的应用程序委托(delegate)中的代码)。如果您的目标是 < iOS 10，则需要删除对持久容器的所有引用。以下是您需要删除的应用程序委托(delegate)内的 iOS 10 变量 perpetualContainer:

class AppDelegate: UIResponder, UIApplicationDelegate {

  ...

    lazy var persistentContainer: NSPersistentContainer = {

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

                    fatalError("Unresolved error \(error), \(error.userInfo)")
                }
            })
            return container
        }()
}

以下是检索 iOS 9 上下文所需的代码:

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator =
        {
            let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
            let url = self.applicationDocumentsDirectory.appendingPathComponent("SingleViewCoreData.sqlite")

            do {
                try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: nil)
            } catch {
                let dict : [String : Any] = [NSLocalizedDescriptionKey        : "Failed to initialize the application's saved data" as NSString,
                                             NSLocalizedFailureReasonErrorKey : "There was an error creating or loading the application's saved data." as NSString,
                                             NSUnderlyingErrorKey             : error as NSError]
                let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
                print("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
                abort()
            }

            return coordinator
    }()

lazy var managedObjectContext: NSManagedObjectContext = {
        let coordinator = self.persistentStoreCoordinator
        var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
        managedObjectContext.persistentStoreCoordinator = coordinator
        return managedObjectContext
    }()

您需要更改的唯一一件事是调用应用程序委托(delegate)中的 saveContext() 方法时引用上下文的方式:

iOS 10 func saveContext () {
让 context = persistentContainer.viewContext
...

iOS 9 func saveContext () {
让上下文=托管对象上下文
...

有一种比较简单的方法来实现两种获取上下文的方法，以便您的代码与操作系统无关，以防您在操作系统 9 之间来回切换目标时不想担心它开发期间有 10 个。看这个blog post有关如何执行此操作的说明/示例代码。