ios - 如何设置 NSBatchDeleteRequest 的 NSBatchDeleteResult 类型？

Question

我有一些执行批量删除请求的核心:

extension NSManagedObject: Clearable {
    /// Clears all objects of this type in coreData
    static func clearAll() {
        let context = AppDelegate.sharedInstance()?.coreDataHelper.objectContext()
        let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: String(describing:self))
        let batchDeleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
        do {
            if let unwrappedContext = context {
                unwrappedContext.shouldDeleteInaccessibleFaults = true
                let result = try unwrappedContext.execute(batchDeleteRequest) as? NSBatchDeleteResult
                DLog("result \(result.debugDescription)")
                switch result!.resultType {
                case .resultTypeCount:
                    DLog("resultTypeCount")
                case .resultTypeObjectIDs:
                    DLog("resultTypeObjectIDs")
                case .resultTypeStatusOnly:
                    DLog("resultTypeStatusOnly")
                }
                if let objectIDArray = result?.result as? [NSManagedObjectID] {
                    let changes = [NSDeletedObjectsKey : objectIDArray]
                    NSManagedObjectContext.mergeChanges(fromRemoteContextSave: changes, into: [unwrappedContext])
                }
                try context?.save()
            }
        } catch let error as NSError {
            DLog("Error removing : \(error), \(error.localizedDescription)")
        }
    }
}

代码运行正常，但是批量删除的结果总是.resultTypeStatusOnly

此处的文档 https://developer.apple.com/library/content/featuredarticles/CoreData_Batch_Guide/BatchDeletes/BatchDeletes.html#//apple_ref/doc/uid/TP40016086-CH3-SW2在执行后更新您的应用程序标题下说

it is important that you notify the application that the objects in memory are stale and need to be refreshed.

为此，结果类型必须是 .resultTypeObjectIDs，才能触发 NSManagedObjectContext.mergeChanges(fromRemoteContextSave: changes, into: [unwrappedContext])部分。只是不清楚你是如何得到它的。

如何设置结果的类型？

Answer 1

您可以在 batchDeleteRequest 上设置 resultType 属性。所以，也来自 https://developer.apple.com/library/content/featuredarticles/CoreData_Batch_Guide/BatchDeletes/BatchDeletes.html :

When the executeRequest completes successfully, a response is received. That response can take one of two forms. The form of the response is deteremined by setting the resultType property on the NSBatchDeleteRequest. The default value is NSStatusOnlyResultType, which returns nothing. The other option is NSBatchDeleteObjectIDsResultType, which returns an array of NSManagedObjectID instances indicating which entities were deleted during the execution.

希望这对您有所帮助。祝你好运!