blocks|key|314603|text|首先，选择一个JSON库来使用，我个人喜欢TouchJSON，但其他几个也很不错。虽然不是很难，但复杂的部分是将托管对象转换为适合转换的结构。我写得很快，所以可能会有一两个错误:)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|314604|您调用的方法是：|314605|-+(NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects;
-+(NSArray*)managedObjectsFromJSONStructure:(NSString*)json+withManagedObjectContext:(NSManagedObjectContext*)moc;|code-block|syntax|javascript|314606|具体实现如下：|314607|-+(NSDictionary*)dataStructureFromManagedObject:(NSManagedObject*)managedObject
{
++NSDictionary+*attributesByName+=+[[managedObject+entity]+attributesByName];
++NSDictionary+*relationshipsByName+=+[[managedObject+entity]+relationshipsByName];
++NSMutableDictionary+*valuesDictionary+=+[[managedObject+dictionaryWithValuesForKeys:[attributesByName+allKeys]]+mutableCopy];
++[valuesDictionary+setObject:[[managedObject+entity]+name]+forKey:@"ManagedObjectName"];
++for+(NSString+*relationshipName+in+[relationshipsByName+allKeys])+{
++++NSRelationshipDescription+*description+=+[[[managedObject+entity]+relationshipsByName]+objectForKey:relationshipName];
++++if+(![description+isToMany])+{
++++++NSManagedObject+*relationshipObject+=+[managedObject+valueForKey:relationshipName];
++++++[valuesDictionary+setObject:[self+dataStructureForManagedObject:relationshipObject]+forKey:relationshipName];
++++++continue;
++++}
++++NSSet+*relationshipObjects+=+[managedObject+objectForKey:relationshipName];
++++NSMutableArray+*relationshipArray+=+[[NSMutableArray+alloc]+init];
++++for+(NSManagedObject+*relationshipObject+in+relationshipObjects)+{
++++++[relationshipArray+addObject:[self+dataStructureForManagedObject:relationshipObject]];
++++}
++++[valuesDictionary+setObject:relationshipArray+forKey:relationshipName];
++}
++return+[valuesDictionary+autorelease];
}

-+(NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects
{
++NSMutableArray+*dataArray+=+[[NSMutableArray+alloc]+init];
++for+(NSManagedObject+*managedObject+in+managedObjects)+{
++++[dataArray+addObject:[self+dataStructureForManagedObject:managedObject]];
++}
++return+[dataArray+autorelease];
}

-+(NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects
{
++NSArray+*objectsArray+=+[self+dataStructuresFromManagedObjects:managedObjects];
++NSString+*jsonString+=+[[CJSONSerializer+serializer]+serializeArray:objectsArray];
++return+jsonString;
}

-+(NSManagedObject*)managedObjectFromStructure:(NSDictionary*)structureDictionary+withManagedObjectContext:(NSManagedObjectContext*)moc
{
++NSString+*objectName+=+[structureDictionary+objectForKey:@"ManagedObjectName"];
++NSManagedObject+*managedObject+=+[NSEntityDescription+insertNewObjectForEntityForName:objectName+inManagedObjectContext:moc];
++[managedObject+setValuesForKeysWithDictionary:structureDictionary];

++for+(NSString+*relationshipName+in+[[[managedObject+entity]+relationshipsByName]+allKeys])+{
++++NSRelationshipDescription+*description+=+[relationshipsByName+objectForKey:relationshipName];
++++if+(![description+isToMany])+{
++++++NSDictionary+*childStructureDictionary+=+[structureDictionary+objectForKey:relationshipName];
++++++NSManagedObject+*childObject+=+[self+managedObjectFromStructure:childStructureDictionary+withManagedObjectContext:moc];
++++++[managedObject+setObject:childObject+forKey:relationshipName];
++++++continue;
++++}
++++NSMutableSet+*relationshipSet+=+[managedObject+mutableSetForKey:relationshipName];
++++NSArray+*relationshipArray+=+[structureDictionary+objectForKey:relationshipName];
++++for+(NSDictionary+*childStructureDictionary+in+relationshipArray)+{
++++++NSManagedObject+*childObject+=+[self+managedObjectFromStructure:childStructureDictionary+withManagedObjectContext:moc];
++++++[relationshipSet+addObject:childObject];
++++}
++}
++return+managedObject;
}

-+(NSArray*)managedObjectsFromJSONStructure:(NSString*)json+withManagedObjectContext:(NSManagedObjectContext*)moc
{
++NSError+*error+=+nil;
++NSArray+*structureArray+=+[[CJSONDeserializer+deserializer]+deserializeAsArray:json+error:&error];
++NSAssert2(error+==+nil,+@"Failed+to+deserialize\n%25@\n%25@",+[error+localizedDescription],+json);
++NSMutableArray+*objectArray+=+[[NSMutableArray+alloc]+init];
++for+(NSDictionary+*structureDictionary+in+structureArray)+{
++++[objectArray+addObject:[self+managedObjectFromStructure:structureDictionary+withManagedObjectContext:moc]];
++}
++return+[objectArray+autorelease];
}|314608|现在，这是递归的，所以如果你不小心，你可以很容易地转换你的整个持久化存储。注意你的关系，并确保它们只在对象树中“向下”移动，这样你才能得到你想要翻译的对象。|314609|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

First, pick a JSON library to use, I personally like TouchJSON but several others out there are quite nice as well. The complicated part, although not very hard, is to convert your managed objects into suitable structures for the conversion. I wrote this real quick so it may have an error or two :)

The methods you call are:

<pre><code>- (NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects;
- (NSArray*)managedObjectsFromJSONStructure:(NSString*)json withManagedObjectContext:(NSManagedObjectContext*)moc;
</code></pre>

And the implementation is as follows:

<pre><code>- (NSDictionary*)dataStructureFromManagedObject:(NSManagedObject*)managedObject
{
 NSDictionary *attributesByName = [[managedObject entity] attributesByName];
 NSDictionary *relationshipsByName = [[managedObject entity] relationshipsByName];
 NSMutableDictionary *valuesDictionary = [[managedObject dictionaryWithValuesForKeys:[attributesByName allKeys]] mutableCopy];
 [valuesDictionary setObject:[[managedObject entity] name] forKey:@"ManagedObjectName"];
 for (NSString *relationshipName in [relationshipsByName allKeys]) {
 NSRelationshipDescription *description = [[[managedObject entity] relationshipsByName] objectForKey:relationshipName];
 if (![description isToMany]) {
 NSManagedObject *relationshipObject = [managedObject valueForKey:relationshipName];
 [valuesDictionary setObject:[self dataStructureForManagedObject:relationshipObject] forKey:relationshipName];
 continue;
 }
 NSSet *relationshipObjects = [managedObject objectForKey:relationshipName];
 NSMutableArray *relationshipArray = [[NSMutableArray alloc] init];
 for (NSManagedObject *relationshipObject in relationshipObjects) {
 [relationshipArray addObject:[self dataStructureForManagedObject:relationshipObject]];
 }
 [valuesDictionary setObject:relationshipArray forKey:relationshipName];
 }
 return [valuesDictionary autorelease];
}

- (NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects
{
 NSMutableArray *dataArray = [[NSMutableArray alloc] init];
 for (NSManagedObject *managedObject in managedObjects) {
 [dataArray addObject:[self dataStructureForManagedObject:managedObject]];
 }
 return [dataArray autorelease];
}

- (NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects
{
 NSArray *objectsArray = [self dataStructuresFromManagedObjects:managedObjects];
 NSString *jsonString = [[CJSONSerializer serializer] serializeArray:objectsArray];
 return jsonString;
}

- (NSManagedObject*)managedObjectFromStructure:(NSDictionary*)structureDictionary withManagedObjectContext:(NSManagedObjectContext*)moc
{
 NSString *objectName = [structureDictionary objectForKey:@"ManagedObjectName"];
 NSManagedObject *managedObject = [NSEntityDescription insertNewObjectForEntityForName:objectName inManagedObjectContext:moc];
 [managedObject setValuesForKeysWithDictionary:structureDictionary];

 for (NSString *relationshipName in [[[managedObject entity] relationshipsByName] allKeys]) {
 NSRelationshipDescription *description = [relationshipsByName objectForKey:relationshipName];
 if (![description isToMany]) {
 NSDictionary *childStructureDictionary = [structureDictionary objectForKey:relationshipName];
 NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc];
 [managedObject setObject:childObject forKey:relationshipName];
 continue;
 }
 NSMutableSet *relationshipSet = [managedObject mutableSetForKey:relationshipName];
 NSArray *relationshipArray = [structureDictionary objectForKey:relationshipName];
 for (NSDictionary *childStructureDictionary in relationshipArray) {
 NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc];
 [relationshipSet addObject:childObject];
 }
 }
 return managedObject;
}

- (NSArray*)managedObjectsFromJSONStructure:(NSString*)json withManagedObjectContext:(NSManagedObjectContext*)moc
{
 NSError *error = nil;
 NSArray *structureArray = [[CJSONDeserializer deserializer] deserializeAsArray:json error:&amp;error];
 NSAssert2(error == nil, @"Failed to deserialize\n%@\n%@", [error localizedDescription], json);
 NSMutableArray *objectArray = [[NSMutableArray alloc] init];
 for (NSDictionary *structureDictionary in structureArray) {
 [objectArray addObject:[self managedObjectFromStructure:structureDictionary withManagedObjectContext:moc]];
 }
 return [objectArray autorelease];
}
</code></pre>

Now this is recursive so you can easily end up translating your entire persistent store if you are not careful. Watch your relationships and make sure that they only go "down" the object tree so that you only get the objects you want translated.

blocks|key|3058467|text|Synchronizing+Core+Data+with+Rails是一个详细的演示文稿，其中包括将核心数据对象序列化/反序列化到JSON或从JSON反序列化的示例代码(跳到核心数据部分的幻灯片55+)。他的示例代码假设了一个没有关系的相当简单的模型，尽管我认为它很容易扩展。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3058468|该演示文稿还详细介绍了如何使核心数据模型与基于REST的web应用程序保持同步，并提供了一些有用的库的指针，包括ObjectiveResource和ASIHTTPRequest。我不确定这是否是你想要做的，但即使是核心数据代码也值得一看。|3058469|entityMap|0|LINK|mutability|MUTABLE|url|http://www.slideshare.net/metaskills/synchronizing-core-data-with-rails|1|http://iphoneonrails.com/|2|http://allseeing-i.com/ASIHTTPRequest/^0|0|Y|0|0|1K|H|1|22|E|2|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@$A|W|B|X|1|Y]|$A|Z|B|10|1|11]]|C|$]]|$1|F|3|-4|5|6|7|12|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]|N|$5|I|J|K|C|$L|O]]|P|$5|I|J|K|C|$L|Q]]]]

<a href="http://www.slideshare.net/metaskills/synchronizing-core-data-with-rails" rel="noreferrer">Synchronizing Core Data with Rails</a> is a detailed presentation that includes sample code for serializing/deserializing your Core Data objects to/from JSON (skip to slide 55 for the Core Data part). His sample code assumes a fairly simple model without relationships, though I think it would be pretty easy to extend.

The presentation also goes into some detail about keeping your Core Data model in sync with a REST-based web application, with pointers to some useful libraries, including <a href="http://iphoneonrails.com/" rel="noreferrer">ObjectiveResource</a> and <a href="http://allseeing-i.com/ASIHTTPRequest/" rel="noreferrer">ASIHTTPRequest</a>. Not sure if that's what you're trying to do, but it's worth a look even for the Core Data code.

blocks|key|315646|text|我只想指出一个小的打字错误，导致代码崩溃，希望这能节省你几分钟的时间。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|315647|-+(NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects+{

++++NSMutableArray+*dataArray+=+[[NSArray+alloc]+init];
++++for+(NSManagedObject+*managedObject+in+managedObjects)+{
++++++++[dataArray+addObject:[self+dataStructureFromManagedObject:managedObject]];
++++}
++++return+[dataArray+autorelease];
}|code-block|syntax|javascript|315648|The+NSMutableArray+*dataArray+=+[[NSArray+alloc]+init];+//+This+should+be+NSMutableArray|offset|length|style|CODE|315649|真的应该是NSMutableArray+*dataArray+=+[[NSMutableArray+alloc]+init];|315650|这就是全部。|315651|谢谢|315652|entityMap^0|0|0|4|2C|0|5|1M|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|Z|8|@$I|10|J|11|K|L]]|9|@]|A|$]]|$1|O|3|P|5|6|7|12|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|T|$]]

I just wanted to point out a small typo, that caused the code to crash, and hopefully this will save you a few min.

<pre><code>- (NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects {

 NSMutableArray *dataArray = [[NSArray alloc] init];
 for (NSManagedObject *managedObject in managedObjects) {
 [dataArray addObject:[self dataStructureFromManagedObject:managedObject]];
 }
 return [dataArray autorelease];
}
</code></pre>

The <code>NSMutableArray *dataArray = [[NSArray alloc] init]; // This should be NSMutableArray</code>

really should be <code>NSMutableArray *dataArray = [[NSMutableArray alloc] init];</code>

that is all.

thank you

blocks|key|312538|text|如果您的托管对象中有一个NSDate，就像上面的一个注释中提到的那样，您在序列化包含NSDate的对象时会遇到问题。一个简单的解决方法是使用objective-c类别向NSDate添加一个JSONDataRepresentation方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|312539|将以下两个文件添加到您的项目中：|312540|NSdate.h:|BOLD|312541|#import+<Foundation/Foundation.h>

@interface+NSDate+(jsondatarepresentation)+

-+(NSData*)+JSONDataRepresentation;

@end|code-block|syntax|javascript|312542|NSDate.m:|312543|#import+"NSDate.h"

@implementation+NSDate+(jsondatarepresentation)

-+(NSData*)+JSONDataRepresentation+{
++++return+[[[NSNumber+numberWithDouble:[self+timeIntervalSince1970]]+stringValue]+dataUsingEncoding:NSUTF8StringEncoding];
}

@end|312544|entityMap^0|C|6|16|6|2C|6|2M|M|0|0|0|9|0|0|0|9|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|14|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|15|8|@$9|16|A|17|B|J]]|D|@]|E|$]]|$1|K|3|L|5|M|7|18|8|@]|D|@]|E|$N|O]]|$1|P|3|Q|5|6|7|19|8|@$9|1A|A|1B|B|J]]|D|@]|E|$]]|$1|R|3|S|5|M|7|1C|8|@]|D|@]|E|$N|O]]|$1|T|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]]|U|$]]

If you have an <code>NSDate</code> in your managed object, as mentioned above in one of the comments, you'll have problems serializing the object containing the <code>NSDate</code>. A simple fix is to add a <code>JSONDataRepresentation</code> method to <code>NSDate</code> using objective-c categories.

Add these two files to your project:

NSdate.h:

<pre><code>#import &lt;Foundation/Foundation.h&gt;

@interface NSDate (jsondatarepresentation) 

- (NSData*) JSONDataRepresentation;

@end
</code></pre>

NSDate.m:

<pre><code>#import "NSDate.h"

@implementation NSDate (jsondatarepresentation)

- (NSData*) JSONDataRepresentation {
 return [[[NSNumber numberWithDouble:[self timeIntervalSince1970]] stringValue] dataUsingEncoding:NSUTF8StringEncoding];
}

@end
</code></pre>

blocks|key|3271843|text|有一个库可以为您完成JSON同步：https://github.com/sixdegrees/lidenbrock|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3271844|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/sixdegrees/lidenbrock^0|H|14|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

There is a lib that does the JSON synchronization for you : <a href="https://github.com/sixdegrees/lidenbrock" rel="nofollow">https://github.com/sixdegrees/lidenbrock</a>

blocks|key|3271865|text|我偶然发现了这篇文章，它工作得很好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3271866|http://touchalicious.com/blog/2009/10/25/turn-core-data-models-into-json.html|offset|length|3271867|由于这是递归的，多对多关系将通过自身循环。为了避免这种情况，我在核心数据模型中的关系的用户信息字典中添加了一个"isExportable“键。然后，您可以检查此键，并选择在没有它的情况下不循环关系。|3271868|​|3271869|📷|atomic|3271870|3271871|if+([property+isKindOfClass:[NSRelationshipDescription+class]])
++++{
++++++++NSRelationshipDescription+*relationshipDescription+=+(NSRelationshipDescription+*)property;

++++++++if+([[[relationshipDescription+userInfo]+objectForKey:@"isExportable"]+boolValue]+==+YES)
++++++++{
++++++++++++NSString+*name+=+[relationshipDescription+name];

++++++++++++if+([relationshipDescription+isToMany])
++++++++++++{
++++++++++++++++NSMutableArray+*arr+=+[properties+valueForKey:name];
++++++++++++++++if+(!arr)
++++++++++++++++{
++++++++++++++++++++arr+=+[[NSMutableArray+alloc]+init];
++++++++++++++++++++[properties+setValue:arr+forKey:name];
++++++++++++++++}

++++++++++++++++for+(NSManagedObject+*o+in+[self+mutableSetValueForKey:name])
++++++++++++++++{
++++++++++++++++++++[arr+addObject:[o+propertiesDictionary]];
++++++++++++++++}
++++++++++++}
++++++++++++else
++++++++++++{
++++++++++++++++NSManagedObject+*o+=+[self+valueForKey:name];
++++++++++++++++[properties+setValue:[o+propertiesDictionary]+forKey:name];
++++++++++++}
++++++++}
++++}
}|code-block|syntax|javascript|3271872|entityMap|0|LINK|mutability|MUTABLE|url|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/5d2ea4bcee8d9c7af0d3e8787b12206d.png|imageAlt^0|0|0|25|0|0|0|0|0|1|1|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@]|9|@$D|17|E|18|1|19]]|A|$]]|$1|F|3|G|5|6|7|1A|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|1B|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|1C|8|@]|9|@$D|1D|E|1E|1|1F]]|A|$]]|$1|M|3|I|5|6|7|1G|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1H|8|@]|9|@]|A|$Q|R]]|$1|S|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|C]]|Z|$5|10|W|11|A|$12|13|14|-4]]]]

I came across this post which works very well.

<a href="http://touchalicious.com/blog/2009/10/25/turn-core-data-models-into-json.html" rel="nofollow noreferrer">http://touchalicious.com/blog/2009/10/25/turn-core-data-models-into-json.html</a> 

Since this is recursive, many-to-many relationships are going to keep looping through themselves. To avoid this, I added an "isExportable" key to the user info dictionary of the relationships in my Core Data model. You can then check for this key and choose to not loop through relationships without it.

<img src="https://i.stack.imgur.com/mEmDO.png" alt="enter image description here">

<pre><code>if ([property isKindOfClass:[NSRelationshipDescription class]])
 {
 NSRelationshipDescription *relationshipDescription = (NSRelationshipDescription *)property;

 if ([[[relationshipDescription userInfo] objectForKey:@"isExportable"] boolValue] == YES)
 {
 NSString *name = [relationshipDescription name];

 if ([relationshipDescription isToMany])
 {
 NSMutableArray *arr = [properties valueForKey:name];
 if (!arr)
 {
 arr = [[NSMutableArray alloc] init];
 [properties setValue:arr forKey:name];
 }

 for (NSManagedObject *o in [self mutableSetValueForKey:name])
 {
 [arr addObject:[o propertiesDictionary]];
 }
 }
 else
 {
 NSManagedObject *o = [self valueForKey:name];
 [properties setValue:[o propertiesDictionary] forKey:name];
 }
 }
 }
}
</code></pre>

blocks|key|312599|text|我想我会快速更新一下这个问题。我遵循了Marcus和Brandon的回答，并提出了这个JSON导出(它仍然使用TouchJSON+)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|312600|-+(NSData*)jsonStructureFromManagedObjects:(NSArray*)managedObjects
{
++++NSArray+*objectsArray+=+[self+dataStructuresFromManagedObjects:managedObjects];
++++NSData+*jsonData++++++=+[[CJSONSerializer+serializer]+serializeArray:objectsArray+error:nil];
++++return+jsonData;
}

-+(NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects
{
++++NSMutableArray+*dataArray+=+[[NSMutableArray+alloc]+init];
++++for+(NSManagedObject+*managedObject+in+managedObjects)+{
++++++++[dataArray+addObject:[self+dataStructureFromManagedObject:managedObject]];
++++}
++++return+dataArray;
}

-+(NSDictionary*)dataStructureFromManagedObject:(NSManagedObject*)managedObject
{
++++NSDictionary+*attributesByName++++++++=+[[managedObject+entity]+attributesByName];
++++NSDictionary+*relationshipsByName+++++=+[[managedObject+entity]+relationshipsByName];
++++NSMutableDictionary+*valuesDictionary+=+[[managedObject+dictionaryWithValuesForKeys:[attributesByName+allKeys]]+mutableCopy];
++++[valuesDictionary+setObject:[[managedObject+entity]+name]+forKey:@"ManagedObjectName"];

++++for+(NSString+*relationshipName+in+[relationshipsByName+allKeys])+{

++++++++NSRelationshipDescription+*description+=+[[[managedObject+entity]+relationshipsByName]+objectForKey:relationshipName];

++++++++if+([[[description+userInfo]+objectForKey:@"isExportable"]+boolValue]+==+YES)+{

++++++++++++if+(![description+isToMany])+{
++++++++++++++++NSManagedObject+*relationshipObject+=+[managedObject+valueForKey:relationshipName];
++++++++++++++++if+(relationshipObject)+{
++++++++++++++++++++[valuesDictionary+setObject:[self+dataStructureFromManagedObject:relationshipObject]+forKey:relationshipName];
++++++++++++++++}

++++++++++++++++continue;
++++++++++++}

++++++++++++NSSet+*relationshipObjects++++++++=+[managedObject+valueForKey:relationshipName];
++++++++++++NSMutableArray+*relationshipArray+=+[[NSMutableArray+alloc]+init];

++++++++++++for+(NSManagedObject+*relationshipObject+in+relationshipObjects)+{
++++++++++++++++[relationshipArray+addObject:[self+dataStructureFromManagedObject:relationshipObject]];
++++++++++++}

++++++++++++[valuesDictionary+setObject:relationshipArray+forKey:relationshipName];

++++++++}

++++}
++++return+valuesDictionary;
}|code-block|syntax|javascript|312601|我不能让导入工作，也许这与我使用Magical+Record的事实有关我不确定，所以我只是循环通过传入的JSON流并手动创建对象……|312602|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Just thought id post a quick update to this question. I followed the Answers by Marcus and Brandon and came up with this for JSON exporting (it uses TouchJSON still):

<pre><code>- (NSData*)jsonStructureFromManagedObjects:(NSArray*)managedObjects
{
 NSArray *objectsArray = [self dataStructuresFromManagedObjects:managedObjects];
 NSData *jsonData = [[CJSONSerializer serializer] serializeArray:objectsArray error:nil];
 return jsonData;
}

- (NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects
{
 NSMutableArray *dataArray = [[NSMutableArray alloc] init];
 for (NSManagedObject *managedObject in managedObjects) {
 [dataArray addObject:[self dataStructureFromManagedObject:managedObject]];
 }
 return dataArray;
}

- (NSDictionary*)dataStructureFromManagedObject:(NSManagedObject*)managedObject
{
 NSDictionary *attributesByName = [[managedObject entity] attributesByName];
 NSDictionary *relationshipsByName = [[managedObject entity] relationshipsByName];
 NSMutableDictionary *valuesDictionary = [[managedObject dictionaryWithValuesForKeys:[attributesByName allKeys]] mutableCopy];
 [valuesDictionary setObject:[[managedObject entity] name] forKey:@"ManagedObjectName"];

 for (NSString *relationshipName in [relationshipsByName allKeys]) {

 NSRelationshipDescription *description = [[[managedObject entity] relationshipsByName] objectForKey:relationshipName];

 if ([[[description userInfo] objectForKey:@"isExportable"] boolValue] == YES) {

 if (![description isToMany]) {
 NSManagedObject *relationshipObject = [managedObject valueForKey:relationshipName];
 if (relationshipObject) {
 [valuesDictionary setObject:[self dataStructureFromManagedObject:relationshipObject] forKey:relationshipName];
 }

 continue;
 }

 NSSet *relationshipObjects = [managedObject valueForKey:relationshipName];
 NSMutableArray *relationshipArray = [[NSMutableArray alloc] init];

 for (NSManagedObject *relationshipObject in relationshipObjects) {
 [relationshipArray addObject:[self dataStructureFromManagedObject:relationshipObject]];
 }

 [valuesDictionary setObject:relationshipArray forKey:relationshipName];

 }

 }
 return valuesDictionary;
}
</code></pre>

I couldn't get the import working, maybe that has something to do with the fact that I'm using Magical Record I'm not sure, so Im just looping through the incoming JSON stream and creating objects manually...

blocks|key|315751|text|Marcus+S.Zarra启发了我把递归的想法带到一个工作版本中。在此版本中，您不需要在CoreData中设置密钥，您可以将其剪切并粘贴到您的项目中:-)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|315752|//+MARK:+-+encoding+and+decoding+CoreData+entity+to+dictionary

func+dataStructureFromManagedObject(+managedObject:NSManagedObject?,+parentEntity:+NSEntityDescription?+=+nil)+->+NSMutableDictionary+{
++++if+(managedObject+!=+nil)+{
++++++++var+attributesByName:+NSDictionary+=+managedObject!.entity.attributesByName
++++++++var+relationshipsByName:+NSDictionary++=+managedObject!.entity.relationshipsByName
++++++++var+valuesImmutableDictionary:+NSDictionary+=+managedObject!.dictionaryWithValuesForKeys(+attributesByName.allKeys)
++++++++var+valuesDictionary:+NSMutableDictionary+=+valuesImmutableDictionary.mutableCopy()+as+NSMutableDictionary
++++++++valuesDictionary.setObject(+managedObject!.entity.name!,+forKey:+"ManagedObjectName")
++++++++for+relationshipNameObject+in+relationshipsByName.allKeys+{
++++++++++++var+relationshipName:+NSString+=+relationshipNameObject+as++NSString
++++++++++++var+relationshipDescription:+NSRelationshipDescription?+=+relationshipsByName.objectForKey(+relationshipName)+as?+NSRelationshipDescription
++++++++++++if+!relationshipDescription!.toMany+{
++++++++++++++++//+ono+to+one
++++++++++++++++if+parentEntity+==+nil+%7C%7C+(relationshipDescription!+as+NSRelationshipDescription).destinationEntity+!=+parentEntity!+{
++++++++++++++++++++//+no+parent+or+relationship+is+"downward"+->+object+for+relationship+must+be+added
++++++++++++++++++++var+relationshipObject:+NSManagedObject?+=+managedObject!.valueForKey(+relationshipName)+as?+NSManagedObject
++++++++++++++++++++var+relationshipObjectDictionary:+NSMutableDictionary+=+self.dataStructureFromManagedObject(+relationshipObject,+parentEntity:+managedObject?.entity)
++++++++++++++++++++valuesDictionary.setObject(+relationshipObjectDictionary,+forKey:+relationshipName)
++++++++++++++++}+else+{
++++++++++++++++++++//+relationship+is+"upward"+->+nothing+to+do
++++++++++++++++}
++++++++++++}+else+{
++++++++++++++++//+one+to+many+->+all+objects+must+be+added
++++++++++++++++var+relationshipObjects:+NSSet+=+managedObject!.mutableSetValueForKey(+relationshipName)
++++++++++++++++var+relationshipArray:NSMutableArray+=+[]
++++++++++++++++for+relationshipObjectRaw+in+relationshipObjects+{
++++++++++++++++++++var+relationshipObject:NSManagedObject?+=+relationshipObjectRaw+as?+NSManagedObject
++++++++++++++++++++if+relationshipObject+!=+nil+&&+!relationshipObject!.entity.isKindOfEntity(+managedObject!.entity)+{
++++++++++++++++++++++++relationshipArray.addObject(self.dataStructureFromManagedObject(+relationshipObject,+parentEntity:+managedObject?.entity))
++++++++++++++++++++}
++++++++++++++++}
++++++++++++++++valuesDictionary.setObject(+relationshipArray,+forKey:+relationshipName)
++++++++++++}
++++++++}
++++++++return+valuesDictionary
++++}+else+{
++++++++return+NSMutableDictionary()
++++}
}

func+managedObjectFromStructure(+structureDictionary:+NSDictionary,+moc:+NSManagedObjectContext,+parentObject:+NSManagedObject?+=+nil)+->+NSManagedObject+{
++++if+structureDictionary.count+>+0+{
++++++++var+objectName:NSString+=+structureDictionary.objectForKey(+"ManagedObjectName")+as+NSString
++++++++var+managedObject:NSManagedObject+=+NSEntityDescription.insertNewObjectForEntityForName(+objectName,+inManagedObjectContext:+moc)+as+NSManagedObject
++++++++var+relationshipsByName:+NSDictionary++=+managedObject.entity.relationshipsByName
++++++++var+realObjectStructure:NSMutableDictionary+=+structureDictionary.mutableCopy()+as+NSMutableDictionary
++++++++realObjectStructure.removeObjectForKey(+"ManagedObjectName")
++++++++for+key+in+realObjectStructure.allKeys+{
++++++++++++//+search+for+"ManagedObjectName"+relationship+entrys+and+delete+them+before+filling+the+managedObject+from+this+structure
++++++++++++for+relationshipName+in+relationshipsByName.allKeys+{
++++++++++++++++if+relationshipName+as+NSString+==+key+as+NSString+{
++++++++++++++++++++realObjectStructure.removeObjectForKey(+key)
++++++++++++++++}
++++++++++++}
++++++++}
++++++++managedObject.setValuesForKeysWithDictionary(+realObjectStructure)
++++++++//+the+main+object+with+attributes+is+created.+Now+care+about+the+relationships
++++++++for+relationshipName+in+managedObject.entity.relationshipsByName.keys+{
++++++++++++var+description:NSRelationshipDescription+=+relationshipsByName.objectForKey(+relationshipName)+as+NSRelationshipDescription
++++++++++++if+!description.toMany+{
++++++++++++++++//+to+one+relationship
++++++++++++++++if+parentObject+==+nil+%7C%7C+description.destinationEntity+!=+parentObject!.entity+{
++++++++++++++++++++//+no+parent+or+relationship+is+"downward"+->+recurse+structure+to+add
++++++++++++++++++++var+childStructureDictionary:NSDictionary+=+structureDictionary.objectForKey(+relationshipName)+as+NSDictionary
++++++++++++++++++++if+childStructureDictionary.count+>+0+{
++++++++++++++++++++++++//+dictionary+not+empty+->+object+must+be+created+and+added
++++++++++++++++++++++++var+childObject:NSManagedObject?+=+self.managedObjectFromStructure(+childStructureDictionary,+moc:+moc,+parentObject:+managedObject)
++++++++++++++++++++++++//+validateForUpdate
++++++++++++++++++++++++var+error:NSError?
++++++++++++++++++++++++if+!managedObject.validateForUpdate(+&error)+{
++++++++++++++++++++++++++++println("Error:+Object+not+in+valid+state+for+update!!!+->+\(error)")
++++++++++++++++++++++++}+else+{
++++++++++++++++++++++++++++managedObject.setValue(+childObject,+forKey:+relationshipName+as+NSString)
++++++++++++++++++++++++}
++++++++++++++++++++}+else+{
++++++++++++++++++++++++//+relationship+is+"upward"+->+nothing+to+do
++++++++++++++++++++}
++++++++++++++++}
++++++++++++}+else+{
++++++++++++++++//+to+many+relationship
++++++++++++++++var+relationshipSet:NSMutableSet+=+managedObject.mutableSetValueForKey(+relationshipName+as+NSString)
++++++++++++++++var+relationshipArray:NSArray+=+structureDictionary.objectForKey(+relationshipName+as+NSString)+as+NSArray
++++++++++++++++for+childStructureDictionary+in+relationshipArray+{
++++++++++++++++++++if+childStructureDictionary.count+>+0+{
++++++++++++++++++++++++//+dictionary+not+empty+->+object+must+be+created+and+added
++++++++++++++++++++++++var+childObject:NSManagedObject+=+self.managedObjectFromStructure(+childStructureDictionary+as+NSDictionary,+moc:+moc,+parentObject:+managedObject)
++++++++++++++++++++++++//+validateForUpdate
++++++++++++++++++++++++var+error:NSError?
++++++++++++++++++++++++if+!managedObject.validateForUpdate(+&error)+{
++++++++++++++++++++++++++++println(+"Error:+Object+not+in+valid+state+for+update!!!+->+\(error)")
++++++++++++++++++++++++}+else+{
++++++++++++++++++++++++++++relationshipSet.addObject(+childObject)
++++++++++++++++++++++++}
++++++++++++++++++++}+else+{
++++++++++++++++++++++++//+no+object+was+behind+the+relationship+->+nothing+to+do
++++++++++++++++++++}
++++++++++++++++}
++++++++++++++++//+save+set
++++++++++++++++managedObject.setValue(+relationshipSet,+forKey:+relationshipName+as+NSString)
++++++++++++}
++++++++}
++++++++//+final+check+validateForUpdate
++++++++var+error:NSError?
++++++++if+!managedObject.validateForUpdate(+&error)+{
++++++++++++println(+"Error:+Object+not+in+valid+state+for+update+although+all+previous+check+are+passed!!!+->+\(error)")
++++++++}
++++++++return+managedObject
++++}+else+{
++++++++println(+"Error:+structure+for+object+was+empty.+this+should+not+happen+at+this+point")
++++++++var+objectName:NSString+=+structureDictionary.objectForKey(+"ManagedObjectName")+as+NSString
++++++++var+managedObject:NSManagedObject+=+NSEntityDescription.insertNewObjectForEntityForName(+objectName,+inManagedObjectContext:+moc)+as+NSManagedObject
++++++++return+managedObject
++++}
}

func+dataStructuresFromManagedObjects(+managedObjects:+NSArray)+->+NSArray+{
++++var+dataArray:NSMutableArray+=+[]
++++for+managedObject+in+managedObjects+{
++++++++dataArray.addObject(+self.dataStructureFromManagedObject(managedObject+as?+NSManagedObject))
++++}
++++return+dataArray
}|code-block|syntax|javascript|315753|这里的关键是将父实体作为参数传递给递归，这样我们就可以决定必须用数据填充哪个关系。因此，这两个函数：dataStructureFromManagedObject和managedObjectFromStructure都可以将CoreData中的任何实体对象编码和解码到字典中，然后再重新编码到对象中。|offset|length|style|CODE|315754|entityMap^0|0|0|1E|U|29|Q|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

Marcus S. Zarra has inspired me to bring the recursive idea to a working version. In this version you don't need to set a key in CoreData and you can cut and paste it in your project :-)

<pre><code>// MARK: - encoding and decoding CoreData entity to dictionary

func dataStructureFromManagedObject( managedObject:NSManagedObject?, parentEntity: NSEntityDescription? = nil) -&gt; NSMutableDictionary {
 if (managedObject != nil) {
 var attributesByName: NSDictionary = managedObject!.entity.attributesByName
 var relationshipsByName: NSDictionary = managedObject!.entity.relationshipsByName
 var valuesImmutableDictionary: NSDictionary = managedObject!.dictionaryWithValuesForKeys( attributesByName.allKeys)
 var valuesDictionary: NSMutableDictionary = valuesImmutableDictionary.mutableCopy() as NSMutableDictionary
 valuesDictionary.setObject( managedObject!.entity.name!, forKey: "ManagedObjectName")
 for relationshipNameObject in relationshipsByName.allKeys {
 var relationshipName: NSString = relationshipNameObject as NSString
 var relationshipDescription: NSRelationshipDescription? = relationshipsByName.objectForKey( relationshipName) as? NSRelationshipDescription
 if !relationshipDescription!.toMany {
 // ono to one
 if parentEntity == nil || (relationshipDescription! as NSRelationshipDescription).destinationEntity != parentEntity! {
 // no parent or relationship is "downward" -&gt; object for relationship must be added
 var relationshipObject: NSManagedObject? = managedObject!.valueForKey( relationshipName) as? NSManagedObject
 var relationshipObjectDictionary: NSMutableDictionary = self.dataStructureFromManagedObject( relationshipObject, parentEntity: managedObject?.entity)
 valuesDictionary.setObject( relationshipObjectDictionary, forKey: relationshipName)
 } else {
 // relationship is "upward" -&gt; nothing to do
 }
 } else {
 // one to many -&gt; all objects must be added
 var relationshipObjects: NSSet = managedObject!.mutableSetValueForKey( relationshipName)
 var relationshipArray:NSMutableArray = []
 for relationshipObjectRaw in relationshipObjects {
 var relationshipObject:NSManagedObject? = relationshipObjectRaw as? NSManagedObject
 if relationshipObject != nil &amp;&amp; !relationshipObject!.entity.isKindOfEntity( managedObject!.entity) {
 relationshipArray.addObject(self.dataStructureFromManagedObject( relationshipObject, parentEntity: managedObject?.entity))
 }
 }
 valuesDictionary.setObject( relationshipArray, forKey: relationshipName)
 }
 }
 return valuesDictionary
 } else {
 return NSMutableDictionary()
 }
}

func managedObjectFromStructure( structureDictionary: NSDictionary, moc: NSManagedObjectContext, parentObject: NSManagedObject? = nil) -&gt; NSManagedObject {
 if structureDictionary.count &gt; 0 {
 var objectName:NSString = structureDictionary.objectForKey( "ManagedObjectName") as NSString
 var managedObject:NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName( objectName, inManagedObjectContext: moc) as NSManagedObject
 var relationshipsByName: NSDictionary = managedObject.entity.relationshipsByName
 var realObjectStructure:NSMutableDictionary = structureDictionary.mutableCopy() as NSMutableDictionary
 realObjectStructure.removeObjectForKey( "ManagedObjectName")
 for key in realObjectStructure.allKeys {
 // search for "ManagedObjectName" relationship entrys and delete them before filling the managedObject from this structure
 for relationshipName in relationshipsByName.allKeys {
 if relationshipName as NSString == key as NSString {
 realObjectStructure.removeObjectForKey( key)
 }
 }
 }
 managedObject.setValuesForKeysWithDictionary( realObjectStructure)
 // the main object with attributes is created. Now care about the relationships
 for relationshipName in managedObject.entity.relationshipsByName.keys {
 var description:NSRelationshipDescription = relationshipsByName.objectForKey( relationshipName) as NSRelationshipDescription
 if !description.toMany {
 // to one relationship
 if parentObject == nil || description.destinationEntity != parentObject!.entity {
 // no parent or relationship is "downward" -&gt; recurse structure to add
 var childStructureDictionary:NSDictionary = structureDictionary.objectForKey( relationshipName) as NSDictionary
 if childStructureDictionary.count &gt; 0 {
 // dictionary not empty -&gt; object must be created and added
 var childObject:NSManagedObject? = self.managedObjectFromStructure( childStructureDictionary, moc: moc, parentObject: managedObject)
 // validateForUpdate
 var error:NSError?
 if !managedObject.validateForUpdate( &amp;error) {
 println("Error: Object not in valid state for update!!! -&gt; \(error)")
 } else {
 managedObject.setValue( childObject, forKey: relationshipName as NSString)
 }
 } else {
 // relationship is "upward" -&gt; nothing to do
 }
 }
 } else {
 // to many relationship
 var relationshipSet:NSMutableSet = managedObject.mutableSetValueForKey( relationshipName as NSString)
 var relationshipArray:NSArray = structureDictionary.objectForKey( relationshipName as NSString) as NSArray
 for childStructureDictionary in relationshipArray {
 if childStructureDictionary.count &gt; 0 {
 // dictionary not empty -&gt; object must be created and added
 var childObject:NSManagedObject = self.managedObjectFromStructure( childStructureDictionary as NSDictionary, moc: moc, parentObject: managedObject)
 // validateForUpdate
 var error:NSError?
 if !managedObject.validateForUpdate( &amp;error) {
 println( "Error: Object not in valid state for update!!! -&gt; \(error)")
 } else {
 relationshipSet.addObject( childObject)
 }
 } else {
 // no object was behind the relationship -&gt; nothing to do
 }
 }
 // save set
 managedObject.setValue( relationshipSet, forKey: relationshipName as NSString)
 }
 }
 // final check validateForUpdate
 var error:NSError?
 if !managedObject.validateForUpdate( &amp;error) {
 println( "Error: Object not in valid state for update although all previous check are passed!!! -&gt; \(error)")
 }
 return managedObject
 } else {
 println( "Error: structure for object was empty. this should not happen at this point")
 var objectName:NSString = structureDictionary.objectForKey( "ManagedObjectName") as NSString
 var managedObject:NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName( objectName, inManagedObjectContext: moc) as NSManagedObject
 return managedObject
 }
}

func dataStructuresFromManagedObjects( managedObjects: NSArray) -&gt; NSArray {
 var dataArray:NSMutableArray = []
 for managedObject in managedObjects {
 dataArray.addObject( self.dataStructureFromManagedObject(managedObject as? NSManagedObject))
 }
 return dataArray
}
</code></pre>

The key here is to pass the parent entity as argument to the recursion, so we can decide which relationship we have to fill with data. So the both functions: <code>dataStructureFromManagedObject</code> and <code>managedObjectFromStructure</code> can encode and decode any entity object from CoreData into a dictionary and back into an object.

I have a core data object graph (consisting of two entities linked by a to-many relationship). 

I was curious, as a relatively inexperienced iPhone developer, whether anyone could recommend an approach, and a suitable JSON implementation for the iPhone, which would allow me to:

<ol>
<li>convert the core data records into a JSON string (whilst maintaining the relationship between the entities); and</li>
<li>convert the JSON string back into core data objects (again preserving the relationship between entities).</li>
</ol>

I have searched, unsuccessfully, for a tutorial/code sample on this point so any assistance would be gratefully received.

JSON and Core Data on the iPhone

JSON

我有一个核心数据对象图(由通过一对多关系链接的两个实体组成)。作为一名相对缺乏经验的iPhone开发人员，我很好奇是否有人能为iPhone推荐一种方法和合适的JSON实现，这将使我能够：将核心数据记录转换为JSON字符串(同时保持实体之间的关系)；将JSON字符串转换回核心数据对象(同样保留实体之间的关系)。我已经在这...

问iPhone上的JSON和核心数据
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