神奇的记录 saveWithBlock：不保存答案

【问题标题】：Magical Record saveWithBlock: not saving神奇的记录 saveWithBlock：不保存
【发布时间】：2014-02-24 13:34:58
【问题描述】：

我无法使用方法 [MagicalRecord saveWithBlock:completion] 保存我的对象。当我切换到使用普通块时，它工作正常。使用版本 2.2develop。

下面的代码有效，我已经注释掉了 saveWithBlock: 特定部分。 executeBlock...: 方法只是包装了 dispatch_async 和 executeBlockOnMainThread: 替换了 completion: 块。

[card.managedObjectContext MR_saveToPersistentStoreAndWait];
//[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) { // Replace this...
[NSObject executeBlockInBackground:^{ // With this...

    Card *localCard = [card MR_inContext:[NSManagedObjectContext MR_contextForCurrentThread]]; // MR_inContext:localContext];
    NSRange range = [localCard.fragment rangeOfString:localCard.term options:NSCaseInsensitiveSearch];
    if (range.location == NSNotFound){
        return;
    }

    NSString *fragmentString = [localCard.fragment stringByReplacingOccurrencesOfString:@" " withString:@"+"];
    NSString *url = [NSString stringWithFormat:@"https://www.lingq.com/api/languages/%@/phrases/?word=%@&frag=%@&start=%@", appDelegate.currentLanguage, localCard.term, fragmentString, @(range.location)];
    NSMutableURLRequest *request = [LQAPI requestForURL:url body:nil HTTPMethod:@"GET"];
    NSData *response = [LQAPI executeURLRequest:request];

    NSDictionary *responseDictionary = [LQAPI dictionaryFromJSONData:response];
    if (responseDictionary == nil){
        return;
    }

    NSArray *phrases = [responseDictionary objectForKey:@"phrases"];
    NSMutableArray *cards = [NSMutableArray array];
    int index = 0;
    for (NSDictionary *d in phrases){
        Card *c = [self cardFromDictionary:d content_id:localCard.content_Id index:index type:BlueCard];
        c.parentID = localCard.mId; // This marks it as a phrase
        [cards addObject:c];
        index++;
    }
    [localCard.managedObjectContext MR_saveToPersistentStoreAndWait]; // This shouldn't be necessary using saveWithBlock: and it didn't help when I tried it.
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"parentID = %@", localCard.mId];
    NSArray *phrases2 = [Card MR_findAllWithPredicate:predicate]; // All the objects appear fine here
    [NSObject executeBlockOnMainThread:^{ // This would have been in the completion block below
        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"parentID = %@", card.mId];
        NSArray *phrases = [Card MR_findAllWithPredicate:predicate]; // This does find phrases
        [delegate didFetchPhrases:phrases forCard:card];
    }];
}];
/*   completion:^(BOOL success, NSError *error) {
 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"parentID = %@", card.mId];
 NSArray *phrases = [Card MR_findAllWithPredicate:predicate]; // This doesn't find any phrases
 [delegate didFetchPhrases:phrases forCard:card];
 }];*/

【问题讨论】：

标签： ios core-data magicalrecord

【解决方案1】：

最后，这是我的错（当然！）。方法 cardFromDictionary: 正在使用 MR_contextForCurrentThread。传递它 localContext 解决了这个问题。

【讨论】：

【解决方案2】：

在 Github 上，我发现在 saveWithBlock: 时获取是不行的：https://github.com/magicalpanda/MagicalRecord/issues/339

【讨论】：

很高兴知道，沃尔克。但是，在完成块中获取是否有问题？第一次提取（phrases2）只是为了调试目的，以显示这些对象确实被创建了。完成的第二个：是重要的。