将已删除的 CKRecord 与 CoreData NSManagedObject 协调一致答案

【问题标题】：Reconcile deleted CKRecord to CoreData NSManagedObject将已删除的 CKRecord 与 CoreData NSManagedObject 协调一致
【发布时间】：2019-11-04 09:37:25
【问题描述】：

我创建了CKQuerySubscriptions 来监控CKRecords 的远程插入、修改和删除。对于插入和修改的记录，这很有效，因为我可以查询CloudKit 以获取受影响的CKRecord，获取关联的NSManagedObject，然后从那里处理插入和修改。

对于已删除的CKRecords，这是一个问题，因为在触发通知时，CKRecord 已从CloudKit 中删除。这意味着获取现已删除的CKRecord 的获取请求失败，因此我无法知道哪个NSManagedObject 与已删除的CKRecord 相关联。

我不知道我是否会以错误的方式处理这一切，是否有更简单的方法来处理所有这些！

【问题讨论】：

标签： core-data cloudkit nsmanagedobject ckrecord ckquerysubscription

【解决方案1】：

这行得通，但感觉有点笨拙。一定有更简单的方法！但如果不是，如果此代码对其他人有用，如果您希望在任何未显示的辅助方法中使用的代码（例如在 +[CoreDataFunctions fetchRecordsForEntityType: withCloudIDs: completion:] 方法中），请随时发表评论；

//Array to hold all cloudIDs of existing NSManagedObject instances
NSMutableArray *cloudIDs = [NSMutableArray array];

//Populate cloudIDs array with the IDs of the existing NSManagedObject instances
for (NSManagedObject *item in self.items) {
    NSUUID *cloudID = [item valueForKey:@"cloudID"];
    [cloudIDs addObject:cloudID];
}

//Array to hold remaining NSManagedObject instances (i.e. the ones which were not deleted)
NSMutableArray *remainingItems = [NSMutableArray array];

//Fetch all remaining CKRecords (i.e. the ones which were not deleted
[CoreDataFunctions fetchRecordsForEntityType:[self managedObjectMonitoringClass] withCloudIDs:cloudIDs completion:^(NSArray<CKRecord *> *results) {
    //For each local NSManagedObject instance
    for (NSManagedObject *item in self.items) {
        //The cloudID for the local NSManagedObject instance
        NSString *localCloudID = [[item valueForKey:@"cloudID"] UUIDString];

        //For each CKRecord in CloudKit
        for (CKRecord *record in results) {
            //The cloudID for the remote CKRecord object
            NSString *remoteCloudID = [record valueForKey:@"CD_cloudID"];

            //If the local and remote cloudIDs match, the local NSManagedObject entity represents a CKRecord which still exists in CloudKit
            //Add the NSManagedObject entity to the remainingItems array
            if ([remoteCloudID isEqualToString:localCloudID]) {
                [remainingItems addObject:item];
                break;
            }
        }
    }

    //Array to hold NSIndexPath objects to be removed from the collectionView
    NSMutableArray *indexPaths = [NSMutableArray array];

    //For each NSManagedObject stored locally
    for (NSManagedObject *item in self.items) {
        //If the remainingItems array does not contain this NSManagedObject, it has been deleted from CloudKit
        //Create and indexPath for this item and add it to the array
        if (![remainingItems containsObject:item]) {
            NSInteger index = [self.items indexOfObject:item];
            [indexPaths addObject:[NSIndexPath indexPathForItem:index inSection:0]];
        }
    }

    dispatch_async(dispatch_get_main_queue(), ^{
        [[self TBcollectionView] performBatchUpdates:^{
            //Set the local items array to whatever is remaining in CloudKit
            self.items = remainingItems;
            //Delete the indexPaths for the items which were deleted
            [[self TBcollectionView] deleteItemsAtIndexPaths:indexPaths];
        } completion:nil];
    });
}];

【讨论】：

【解决方案2】：

我使用带有远程通知和 CKFetchRecordZoneChangesOperation 的订阅。

如果调用“application(didReceiveRemoteNotification:)”方法，如果构建并触发“CKFetchRecordZoneChangesOperation”。

有几个完成处理程序。一种用于更新记录（添加/修改），另一种用于已删除记录。

此处理程序称为“recordWithIDWasDeletedBlock”，并为已删除的每条记录调用，并提供已删除记录的记录ID。有了这些信息，您应该能够处理您需要的内容。

【讨论】：