Swift 3.0 Coredata - Appdelegate & managedObjectContext 抛出 EXC_BAD_ACCESS 错误

Posted 2023-03-13

【中文标题】Swift 3.0 Coredata - Appdelegate & managedObjectContext 抛出 EXC_BAD_ACCESS 错误

【英文标题】：Swift 3.0 Coredata - Appdelegate & managedObjectContext throws EXC_BAD_ACCESS error

【发布时间】：2017-01-30 17:43:41

【问题描述】：

我正在开发我正在使用 coredata 的应用程序。在 coredata 中声明 managedObjectContext 时，我遇到了错误的访问错误。请也找到我的代码，

Model类中使用的代码：

func getAppDelegate() -> AppDelegate

    return UIApplication.shared.delegate as! AppDelegate

let managedContext = getAppDelegate().managedObjectContext(用于其中一个函数) - 此行抛出错误访问错误

Appdelegate 中使用的核心数据函数：

lazy var applicationDocumentsDirectory: URL = 
    // The directory the application uses to store the Core Data store file. This code uses a directory named "com.swaas.MyApp" 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: "MyApp", 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()
        
    

注意：并非总是在随机时间抛出错误的访问错误。即使在删除应用程序后，系统也会抛出错误。

【问题讨论】：

调试控制台中正在打印什么消息？ （而不是使用!，你可以测试看看你是否有一个有效的值。）

【参考方案1】：

尝试访问主线程上的NSManagedObjectContext， 也许您正试图从另一个参数中捕获此参数？

如果您可以发布调用您发布的行的方法，那就太好了：

let managedContext = getAppDelegate().managedObjectContext