看来，这个错误已经出现了很多次了。这个问题最突出的答案似乎是
RestKit 0.20 — CoreData: error: Failed to call designated initializer on NSManagedObject class
但是，发布的解决方案对我不起作用。但是，让我们从头开始:
我想将文件上传到服务器。我想解析响应以确保已成功上传。如果没有，我稍后再试。我的模型为此目的有一个名为NSNumber *sentToServer的布尔变量(在CoreData中，BOOL保存为NSNumber)。
因为我不知道发送是否会成功，所以在通过RestKit发送实体之前，我总是先将其保存到CoreData模型中。
POST请求成功后，服务器将返回一个JSON字符串，如下所示:
{"id":14,"created":true}
请注意，当然，尚未在CoreData模型上设置ID，因此
id和created都是我的模型的新信息。这是我的模型:
@interface Recording : NSManagedObject
@property (nonatomic, retain) NSString * audioFilePath;
@property (nonatomic, retain) NSDate * createdAt;
@property (nonatomic, retain) NSString * deviceId;
@property (nonatomic, retain) NSString * deviceType;
@property (nonatomic, retain) NSNumber * recordingId;
@property (nonatomic, retain) NSNumber * sentToServer;
@end
这是我的设置方法:
NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"HTRecording" ofType:@"momd"]];
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
NSString *storePath = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"AudioModel.sqlite"];
NSError *error = nil;
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
if (![managedObjectStore addSQLitePersistentStoreAtPath:storePath
fromSeedDatabaseAtPath: nil
withConfiguration:nil
options:options
error:&error]) {
NSAssert(NO, @"Managed object store failed to create persistent store coordinator: %@", error);
}
[managedObjectStore createManagedObjectContexts];
// Configure MagicalRecord to use RestKit's Core Data stack
[NSPersistentStoreCoordinator MR_setDefaultStoreCoordinator:managedObjectStore.persistentStoreCoordinator];
[NSManagedObjectContext MR_setRootSavingContext:managedObjectStore.persistentStoreManagedObjectContext];
[NSManagedObjectContext MR_setDefaultContext:managedObjectStore.mainQueueManagedObjectContext];
NSString *databaseUrl = @"http://localhost:3000";
RKObjectManager *objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:databaseUrl]];
objectManager.managedObjectStore = managedObjectStore;
objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
// Setup mapping
RKEntityMapping* recordingRequestMapping = [RKEntityMapping mappingForEntityForName:@"Recording" inManagedObjectStore:managedObjectStore];
[recordingRequestMapping addAttributeMappingsFromDictionary:@{
@"device_id": @"deviceId",
@"device_type": @"deviceType" }];
RKRequestDescriptor *requestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[recordingRequestMapping inverseMapping]
objectClass:[Recording class]
rootKeyPath:@"recording"];
[objectManager addRequestDescriptor:requestDescriptor];
RKEntityMapping* recordingResponseMapping = [RKEntityMapping mappingForEntityForName:@"Recording" inManagedObjectStore:managedObjectStore];
[recordingResponseMapping addAttributeMappingsFromDictionary:@{
@"created": @"sentToServer",
@"id": @"recordingId"}];
recordingResponseMapping.identificationAttributes = @[@"recordingId"];
RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:recordingResponseMapping
pathPattern:@"/audio.json"
keyPath:nil
statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:responseDescriptor];
首先，这是一个令人惊讶的冗长的设置代码，它应该很常见(只是init RestKit和MagicalRecord)。但是我离题了...
整个上传过程运行良好。请求映射很好，所有内容(包括附件)都存储在服务器上。请注意，请求映射不包含文件，因为它们是通过多部分post方法发送的。同样，该部分工作正常。这是上传文件的代码:
RKObjectManager *manager = [RKObjectManager sharedManager];
NSMutableURLRequest *request;
request = [manager multipartFormRequestWithObject:recording
method:RKRequestMethodPOST
path:@"audio.json"
parameters:nil
constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
[formData appendPartWithFileData:[[NSFileManager defaultManager] contentsAtPath:recording.audioFilePath]
name:@"recording[audio]"
fileName:[recording.audioFilePath lastPathComponent]
mimeType:@"audio/m4a"];
}];
RKObjectRequestOperation *operation = [manager objectRequestOperationWithRequest:request
success:^(RKObjectRequestOperation *op, RKMappingResult *mapping) {
NSLog(@"successfully saved file on the server");
}
failure:^(RKObjectRequestOperation *op, NSError *error){
NSLog(@"some weird error");
}];
[manager enqueueObjectRequestOperation:operation];
将响应映射到对象变得困难。如果没有匹配的响应映射，日志输出将包含一个错误，无法处理响应(意外)。但是，使用匹配的响应映射，应用程序将崩溃。这是堆栈跟踪:
#11 0x2f6482d6 in -[NSObject(NSKeyValueCoding) valueForKeyPath:] ()
#12 0x00113b9a in -[RKMappingOperation shouldSetValue:forKeyPath:usingMapping:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMappingOperation.m:436
#13 0x00114e40 in -[RKMappingOperation applyAttributeMapping:withValue:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMappingOperation.m:536
#14 0x00115fd4 in -[RKMappingOperation applyAttributeMappings:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMappingOperation.m:577
#15 0x0011c988 in -[RKMappingOperation main] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMappingOperation.m:948
#16 0x2f655d0a in -[__NSOperationInternal _start:] ()
#17 0x0010cd5a in -[RKMapperOperation mapRepresentation:toObject:atKeyPath:usingMapping:metadata:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:256
#18 0x0010b6aa in -[RKMapperOperation mapRepresentation:atKeyPath:usingMapping:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:176
#19 0x0010ddc8 in -[RKMapperOperation mapRepresentationOrRepresentations:atKeyPath:usingMapping:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:314
#20 0x0010e552 in -[RKMapperOperation mapSourceRepresentationWithMappingsDictionary:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:359
#21 0x0010ee72 in -[RKMapperOperation main] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:398
#22 0x2f655d0a in -[__NSOperationInternal _start:] ()
#23 0x00100e70 in -[RKObjectResponseMapperOperation performMappingWithObject:error:] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/Network/RKResponseMapperOperation.m:345
#24 0x000ff4e6 in -[RKResponseMapperOperation main] at /Users/earthnail/development/RestkitFileUpload/Pods/RestKit/Code/Network/RKResponseMapperOperation.m:297
#25 0x2f655d0a in -[__NSOperationInternal _start:] ()
调试器在
SIGABRT中以[RKMappingOperation shouldSetValue:forKeyPath:usingMapping:]停止的行是:id currentValue = [self.destinationObject valueForKeyPath:keyPath];
请注意，当我按照https://stackoverflow.com/a/13734348/487556中的建议设置断点时，从未达到该断点。这意味着响应映射的路径没有问题。
我可以想象这里发生了几件事:
有什么建议么？
最佳答案
我知道距您提出要求已经有一段时间了，也许您已经找到了解决方法，但是我遇到了同样的情况并找到了解决方案。
问题来自于在使用NSManagedObjects时使用objectRequestOperationWithRequest:success:failure:方法的事实。因此，RestKit尝试在映射操作期间实例化常规NSObject，这会导致崩溃。
尝试改用managedObjectRequestOperationWithRequest:managedObjectContext:success:failure:，情况应该会更好。
关于ios - RestKit 0.20 — CoreData:错误:无法再次调用NSManagedObject类上的指定初始化程序，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/18258698/