13

我正在新的 Xcode 8 中开发一个应用程序，我注意到一件显而易见的事情。Xcode 使用最新的 API 参考为我生成了 Core Data。因此，如果我将部署目标更改为 iOS 8 或 9，它会发生冲突并建议我使用括号：AVAILABLE我的核心数据代码。这意味着我必须从以前的 API 中从头开始编写 Core Data 代码。有没有人有 AppDelegate 的模板，或者可以让 Xcode 生成它们？提前致谢！

4

3 回答 3

49

因为没有人应该下载 Xcode 7，安装它，开始一个新项目，并将模板代码移植到 swift 3，只是为了在仍然支持 iOS 8 和 9 的同时利用核心数据：

来自 AppDelegate.swift 的 Swift 2 Core Data 模板方法：

lazy var applicationDocumentsDirectory: NSURL = {
    // 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 = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .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 = NSBundle.mainBundle().URLForResource("coreDataTemplate", withExtension: "momd")!
    return NSManagedObjectModel(contentsOfURL: 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.URLByAppendingPathComponent("SingleViewCoreData.sqlite")
    var failureReason = "There was an error creating or loading the application's saved data."
    do {
        try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
    } catch {
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason

        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 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()
        }
    }
}

转换为 swift 3：

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
    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()
        }
    }
}
于 2016-10-02T05:44:28.487 回答
10

感谢DCToDaylight 的回答。我制作了这个文件，你可以简单地拖放它。我还将我的托管对象上下文设为静态，并将我的 init 方法设为私有。这样某人就不会意外地实例化一个新的上下文。

getContext每次使用核心数据做某事时，调用的函数都会变得更容易。

创建一个静态 managedObjectContext、一个单独的文件和函数的想法来自这个 YouTube 教程。

对于这个例子，我创建了一个名为的新文件DatabaseController.swift并将所有这些代码放在那里。这只会使我的代码更易于管理和阅读。您也可以从// MARK: - Core Data stack文件底部复制并替换您的类似代码，AppDelegate.swift它会起作用。

import Foundation
import CoreData

class DatabaseController {

    private init() {

    }

    class func getContext () -> NSManagedObjectContext {
        return DatabaseController.managedObjectContext
    }
    // MARK: - Core Data stack

    static var managedObjectContext: NSManagedObjectContext = {

        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]
        }()

        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: "YOUR_APP_NAME", withExtension: "momd")!
            return NSManagedObjectModel(contentsOf: modelURL)!
        }()

        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: managedObjectModel)
            let url = 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
        }()

        // 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 = persistentStoreCoordinator
        var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
        managedObjectContext.persistentStoreCoordinator = coordinator
        return managedObjectContext
    }()

    // MARK: - Core Data Saving support

    class 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()
            }
        }
    }
}

话虽如此，由于显而易见的原因，您不能使用 NSPersistantContainer，因此您必须通过使用 managedObjectContext 来使用 Core Data Stack 方法。

于 2017-01-05T21:07:02.453 回答
0

如果你想快速解决这个问题，你只需要添加一个包含核心数据通用函数的目标 c 类，以获得 NSManagedObjectContext 和 NSPersistentStoreCoordinator 的引用。（您可以在 SO 或其他网站上找到代码，如果您需要该课程，请联系我。）

添加类后使用@Available 10 子句，并在其他部分添加代码以参考上述模型。

让我知道是否有人发现它有任何问题。

于 2017-07-01T07:52:56.500 回答