Question

我收到一个奇怪的错误（NSFSagedObject（MagicalRecord）中的CFStringGetLength的EXC_BAD_ACCESS MR_executeFetchRequest：inContext :)我无法理解何时尝试从JSON文件导入数据......

NSManagedObjectContext *opContext = [NSManagedObjectContext MR_contextForCurrentThread];

NSString *jsonPath = [[NSBundle mainBundle] pathForResource:@"DefaultData"
                                                         ofType:@"json"];
NSData *data = [NSData dataWithContentsOfFile:jsonPath];

NSError *parseError;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&parseError];

NSArray *dataTypes = [json objectForKey:@"dataTypes"];

[MagicalRecord saveWithBlockAndWait:^(NSManagedObjectContext *localContext) {
    for (NSDictionary *obj in dataTypes) {
        [BTDataType MR_importFromObject:obj inContext:localContext];
    }
}];

NSError *saveError;
[opContext save:&saveError];

实体非常简单，只有两个属性：importKey（int16）和name（String）......

JSON就像......

{
    "dataTypes":[
         {
             "importKey":1000,
             "name":"DataType A"
         },
         {
             "importKey":1001,
             "name":"DataType B"
         },
         {
             "importKey":1002,
             "name":"DataType C"
         },
         {
             "importKey":1003,
             "name":"DataType D"
         }
    ]
}

Answer 1

我有同样的问题。我能够通过在Xcode中选择我的实体然后添加userInfo键/值来解决它。因此，对于您，您需要添加'relatedByAttribute':'importKey'的键/值。

请参阅我的回答https://stackoverflow.com/a/18370739/442695

使用MagicalRecord导入数据

1 个答案: