使用 arrayController 结果 "Cannot perform operation without a managed object context"

Question

我正在 Swift 2.2 中重写我以前的 objC 应用程序。这是 cocoa 应用程序，我在其中使用 NSArrayController 来填充 NSTableView 内容。错误很明显，尽管类似的设置在 Objective C app.

中有效

这是我的 AppDelegate：

 var coreStack:AP_CoreDataStack!
var mainContext:NSManagedObjectContext!

override func awakeFromNib() {
coreStack = AP_CoreDataStack(){ (result) -> () in
        if result {
            self.mainContext = self.coreStack.mainContext
        }
    }
}

核心数据堆栈的设置

// MARK: - AP_CoreDataStack Class
class AP_CoreDataStack {

let mainContext: NSManagedObjectContext
let mastercontext: NSManagedObjectContext
var workerContext: NSManagedObjectContext?


internal typealias CallBack = (result:Bool) -> Void
init ( callback: CallBack) { 


    let modelURL = NSBundle.mainBundle().URLForResource("appNameSWIFT", withExtension: "momd")
    if (modelURL == nil) {
        print("Failed to initialize modelURL: \(modelURL)")
    }

    let mom = NSManagedObjectModel(contentsOfURL: modelURL!)
    if mom == nil {
        print("Failed to initialize model")
    }

    let psc = NSPersistentStoreCoordinator(managedObjectModel: mom!)

    mastercontext = NSManagedObjectContext(concurrencyType: .PrivateQueueConcurrencyType)
    mastercontext.persistentStoreCoordinator = psc

    mainContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
    mainContext.parentContext = mastercontext


    // add store to psc in background thread
    let qualityOfServiceClass = QOS_CLASS_BACKGROUND
    let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
    dispatch_async(backgroundQueue, {
        //BACKGROUND THREAD
        // adding store to persistent store coordinator
        let options = [NSInferMappingModelAutomaticallyOption:true,
            NSMigratePersistentStoresAutomaticallyOption:true]
        do {
            // store = try psc.addP
            try psc.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: applicationDocumentDirectory(), options: options)
        } catch let error as NSError {
            print("Error: Failed to load store \(error.localizedDescription), \(error.userInfo)")
        }

        // MAIN THREAD
        dispatch_async(dispatch_get_main_queue(), { () -> Void in
            // On Main thread pass message that stack setup is complete
            callback(result: true)
        })
    })


}

以上是我的 Obj C 代码的 Swift 版本，运行良好。我在 xib 文件中有一个 NSArrayController 绑定到 IB 中的 Entity 和 NSManagedObjectContext:

// Bind To Delegate
self.mainContext

似乎数组控制器在初始化之前正在访问 mainContext，但这与在 objC 中工作的设置相同，所以为什么它在 Swift.

中导致错误

编辑：我正在使用常规的 xib 文件。

编辑 2：

显然 mainContext 不是 nil，因为在这里调用它是正确的

    func applicationDidFinishLaunching(aNotification: NSNotification) {
    // Insert code here to initialize your application

    let request = NSFetchRequest(entityName: "AP_EntityA")
    let list:Array<AnyObject>
    do {
        list = try coreStack.mainContext.executeFetchRequest(request)
        for item in list {
            let product = item as! AP_EntityA
           print("item name is: \(product.uniqueName)")
        }
    } catch let error as NSError {
        // failure
        print("Fetch failed: \(error.localizedDescription)")
    }

}

Answer 1

添加 dynamic 关键字使 Swift 属性符合 KVO。

dynamic var mainContext:NSManagedObjectContext!

使用 arrayController 结果 "Cannot perform operation without a managed object context"

Using arrayController results in "Cannot perform operation without a managed object context"

cocoa

core-data

nsarraycontroller

swift