使用 Objective-C 在 Xcode 中使用 RestKit 映射嵌套对象

Question

在 mja 的帮助下，我成功地使用 RestKit 和 Objective-C 设置了简单的对象映射。请看我之前的问题here。

我的下一步是尝试以同样的方式处理嵌套的 JSON。

我的 JSON 看起来像这样，外部是带有一些嵌套“投票”的 CandidatePhrase：

{ "Id":33696,
"Phrase": "phrase",
"BadCount":0,
"Votes":[{"Id":447,"OriginalId":33696,"Votes":2,"Translation":"translation 1"},
{"Id":746,"OriginalId":33696,"Votes":1,"Translation":"translation 2"},
{"Id":747,"OriginalId":33696,"Votes":1,"Translation":"translation 3"}
]}

我在 AppDelegate 中创建了如下关系：

[candidatePhraseMapping mapKeyPath:@"votes" toRelationship:@"vote" withMapping:voteMapping];

当我在控制器中调用 make 我的请求时，我可以处理 CandidatePhrase 的其余部分，但我不确定如何将嵌套的“投票”对象映射到一个数组中，以便我可以在其中使用它们一个表格视图

（类似这样的伪代码...）

// Store the votes in an array
_votes = [[NSArray alloc] initWithObjects:myCandidatePhrase.votes, nil];

这是我的 CandidatePhrase 对象

@interface CandidatePhrase : NSObject

@property (nonatomic, retain) NSNumber* ident;
@property (nonatomic, retain) NSNumber* badcount;
@property (nonatomic, retain) NSString* phrase;
@property (nonatomic, retain) NSArray* votes;

@end

和我的投票对象

@interface Vote : NSObject

@property (nonatomic, retain) NSNumber* ident;
@property (nonatomic, retain) NSNumber* originalId;
@property (nonatomic, retain) NSNumber* votecount;
@property (nonatomic, retain) NSString* translation;

+ (id)voteWithTranslationId:(NSNumber *)ident translation:(NSString *)translation;

@end

任何帮助将不胜感激。

编辑

下面是我的映射代码

// Votes Mapping

RKObjectMapping* voteMapping = [RKObjectMapping mappingForClass:[Vote class]];
[voteMapping mapKeyPath:@"Id" toAttribute:@"ident"];
[voteMapping mapKeyPath:@"OriginalId" toAttribute:@"originalId"];
[voteMapping mapKeyPath:@"Votes" toAttribute:@"votecount"];
[voteMapping mapKeyPath:@"Translation" toAttribute:@"translation"];

[[manager mappingProvider] addObjectMapping:voteMapping];

// Candidate Phrase Mapping
RKObjectMapping *candidatePhraseMapping = [RKObjectMapping mappingForClass:[CandidatePhrase class]];

[candidatePhraseMapping mapKeyPath:@"Id" toAttribute:@"ident"];
[candidatePhraseMapping mapKeyPath:@"Phrase" toAttribute:@"phrase"];
[candidatePhraseMapping mapKeyPath:@"BadCount" toAttribute:@"badcount"];

[candidatePhraseMapping mapKeyPath:@"Votes" toRelationship:@"votes" withMapping:voteMapping];

[[manager mappingProvider] addObjectMapping:candidatePhraseMapping];

为了清楚起见，下面是我尝试访问控制器上的投票项的方式

- (void)objectLoader:(RKObjectLoader*)objectLoader didLoadObject:(id)object 
{ 
    CandidatePhrase *myCandidatePhrase = (CandidatePhrase*)object;
    self.candidateText.text = myCandidatePhrase.phrase; <-- works fine

    _votes = [[NSArray alloc] initWithObjects:myCandidatePhrase.votes, nil];
    for (id o2 in _votes) { 
        //Vote *vote = o2; 
        NSLog(@"Item name: %@", o2); <-- sees object but crashes
    }

    NSLog(@"Votes: %@", myCandidatePhrase.votes); 
    _votes = [[NSArray alloc] initWithObjects:myCandidatePhrase.votes, nil];
     [_votesTableView reloadData];
 } 

我的表绑定了

Vote *vote = [_votes objectAtIndex:indexPath.row];
cell.textLabel.text = vote.translation;

Answer 1

您不需要手动管理嵌套的 NSArray。我相信问题可能只是一个简单的拼写错误，因为您将 keyPath 映射为“votes”，但您的 json 包含带有大写“V”的“Votes”。

[candidatePhraseMapping mapKeyPath:@"Votes" toRelationship:@"votes" withMapping:voteMapping];

如果这没有帮助，请随时发表评论并通过voteMapping 更新您的问题。

另外，didLoadObject 的内容也可以简化：

//in .h file
@property (nonatomic, retain) NSArray* votes;

// in implementation
@synthesize votes;

...
- (void)objectLoader:(RKObjectLoader*)objectLoader didLoadObject:(id)object 
{ 
    CandidatePhrase *myCandidatePhrase = (CandidatePhrase*)object;
    self.candidateText.text = myCandidatePhrase.phrase;
    self.votes = myCandidatePhrase.votes;
}