Question

在CoreData文档中，我有一个实体SpaceLocation，它由不同的SpaceLocations组成。其中一个是默认/当前编辑文档所必需的。

它在主Document.swift中定义为：

03-20 13:07:32.507 22867-23024/? E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #3
                                               Process: com.example.justcopy, PID: 22867
                                               java.lang.RuntimeException: An error occurred while executing doInBackground()
                                                   at android.os.AsyncTask$3.done(AsyncTask.java:330)
                                                   at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
                                                   at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
                                                   at java.util.concurrent.FutureTask.run(FutureTask.java:242)
                                                   at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:255)
                                                   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
                                                   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
                                                   at java.lang.Thread.run(Thread.java:776)
                                                Caused by: java.util.ConcurrentModificationException
                                                   at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1232)
                                                   at java.util.TreeMap$EntryIterator.next(TreeMap.java:1268)
                                                   at java.util.TreeMap$EntryIterator.next(TreeMap.java:1267)
                                                   at com.example.adnaneg.copytoclipboard.MainActivity$DeleteData.doInBackground(MainActivity.kt:309)
                                                   at com.example.adnaneg.copytoclipboard.MainActivity$DeleteData.doInBackground(MainActivity.kt:305)
                                                   at android.os.AsyncTask$2.call(AsyncTask.java:316)
                                                   at java.util.concurrent.FutureTask.run(FutureTask.java:237)
                                                   at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:255) 
                                                   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133) 
                                                   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607) 
                                                   at java.lang.Thread.run(Thread.java:776)

并在SpaceLocation类中：

@objc var defaultSpaceLocation: SpaceLocation {

    return SpaceLocation.defaultSpaceLocation(in: managedObjectContext!)
}

@objc var currentSpaceLocation: SpaceLocation {
    get {
        if _currentSpaceLocation == nil {
            willChangeValue(for: \Document.currentSpaceLocation)
            _currentSpaceLocation = defaultSpaceLocation
            didChangeValue(for: \Document.currentSpaceLocation)
        }
        return _currentSpaceLocation!
    }

    set {
        willChangeValue(for: \Document.currentSpaceLocation)
        _currentSpaceLocation = newValue
        didChangeValue(for: \Document.currentSpaceLocation)
    }
}

我通过以下方式访问currentSpaceLocation：

class func defaultSpaceLocation(in moc: NSManagedObjectContext) -> SpaceLocation {
        let spaceLocationsRequest = NSFetchRequest<SpaceLocation>(entityName: "SpaceLocation")
        var result:SpaceLocation? = nil
        do {
            let spaceLocations = try moc.fetch(spaceLocationsRequest)
            result = spaceLocations.filter {$0.isBaseLocation}.first!
        }
        catch {
            Swift.print("•••• ERROR ••••", #file, #function, "Couldn't get Default Location")
        }

        return result!
    }
}

但仅当文档位于前台时才有效。当应用进入后台(NSDocumentController.shared.currentDocument as?Document)?.currentSpaceLocation变为NSDocumentController.shared.currentDocument时，我无法访问nil。知道如何解决这个问题吗？

如何从另一个类访问Document.swift中的变量？

0 个答案: