使用RestKit和Objective-C将JSON响应映射到对象 [英] Mapping a JSON response to an object using RestKit and Objective-C

问题描述

我对Objective-C相对较新，并且正在尝试使用RestKit从Web服务接收JSON响应.我已成功将数据接收回我的应用程序，看起来像这样查看响应:

I am relatively new to Objective-C and am attempting to use RestKit to receive a JSON response from a web service. I have successfully received the data back to my application, which looks like this viewing the response:

{id:"1","Translation":"Test"}

我想将此翻译映射到我的应用程序中的翻译"对象，但是尝试了几种不同的方法，但不确定如何实现.

I would like to map this translation to my "Translation" object in my application, but have tried a few different ways but am not sure how to achieve this.

所以我的问题是:

1. 如何将该响应映射到我的翻译对象
2. 我能正确执行此操作吗，创建一种方法来完成此调用，而不是我的视图控制器?

我的翻译对象

@implementation Translation  

@synthesize identifier = _identifier;
@synthesize translation = _translation;

- (NSDictionary*)elementToPropertyMappings {  
return [NSDictionary dictionaryWithKeysAndObjects:  
        @"id", @"identifier",  
        @"translation", @"translation",
        nil];  
}  

@end

我的翻译方法

- (NSString *)performTranslation:(NSString *)translation
{

NSString *data = [[NSString alloc] initWithFormat:@"{\"SourceId\": \"%@\",\"RegionTag\": \"%@\",\"InputString\": \"%@\"}", @"1", @"Glasgow", translation];
NSString *post = data;

RKRequest *MyRequest = [[RKRequest alloc] initWithURL:[[NSURL alloc] initWithString:@"http://my.url.com/Translation/Translate"]];
MyRequest.method = RKRequestMethodPOST;
MyRequest.HTTPBodyString = post;
MyRequest.additionalHTTPHeaders = [[NSDictionary alloc] initWithObjectsAndKeys:@"application/json", @"Content-Type", @"application/json", @"Accept", nil];
[MyRequest send];

RKResponse *Response = [MyRequest sendSynchronously];

return Response.bodyAsString; <--- looking to map this to translation object here

}

推荐答案

您的代码段似乎有些过时了.我强烈建议您依次阅读最新的对象映射指南充分利用RestKit的最大潜力-尤其是无需KVC进行映射的部分.

The snippet of your code seems a bit outdated. I strongly recommend reading the newest Object Mapping guide in order to leverage RestKit into it's fullest potential - especially the part Mapping without KVC.

为了使用RestKit发布对象并接收答案，我们定义了一个TranslationRequest类，该类将保存我们的请求& Translation保持我们的答复.

In order to post an object with RestKit and receive back an answer, we define a TranslationRequest class that will hold our request & Translation to hold our response.

首先，我们设置RKObjectManager和映射(我通常在AppDelegate中执行此操作):

Firstly, we set up our RKObjectManager and mappings (i usually do this in my AppDelegate):

RKObjectManager *manager = [RKObjectManager objectManagerWithBaseURL:kOurBaseUrl];
[manager setSerializationMIMEType:RKMIMETypeJSON];
//this is a singleton, but we keep the manager variable to avoid using [RKObjectManager sharedManager] all the time

//Here we define a mapping for the request. Note: We define it as a mapping from JSON to entity and use inverseMapping selector later.
RKObjectMapping *translationRequestMapping = [RKObjectMapping mappingForClass:[TranslationRequest class]];
[translationRequestMapping mapKeyPath:@"RegionTag" toAttribute:@"regionTag"];
...
[[manager mappingProvider] setSerializationMapping:[translationRequestMapping inverseMapping] forClass:[TranslationRequest class]];

//now we define the mapping for our response object
RKObjectMapping *translationMapping = [RKObjectMapping mappingForClass:[Translation class]];
[translationMapping mapKeyPath:@"id" toAttribute:@"identifier"];
[translationMapping mapKeyPath:@"Translation" toAttribute:@"translation"];
[[manager mappingProvider] addObjectMapping:mapping];

//finally, we route our TranslationRequest class to a given endpoint
[[manager router] routeClass:[TranslationRequest class] toResourcePath:kMyPostEndpoint];

这足以完成必要的设置.我们可以在代码中的任何地方(例如，在任何控制器中)调用后端，如下所示:

This should be enough of the necessary setup. We can call our backend anywhere in the code (e.g. in any controller) like this:

//we create new TranslationRequest
TranslationRequest *request = [[TranslationRequest alloc] init];
[request setRegionTag:@"Hello"];
....
//then we fetch the desired mapping to map our response with
RKObjectMapping *responseMapping = [[RKObjectManager sharedManager].mappingProvider objectMappingForClass:class]
//and just call it. Be sure to let 'self' implement the required RKObjectManagerDelegate protocol
[[RKObjectManager sharedManager] postObject:request mapResponseWith:responseMapping delegate:self];]

尝试这种方法，让我知道您是否需要任何帮助..我无法完全测试它，因为我没有任何合适的后端可以返回响应，但是从RestKit日志中判断这应该可行.

Try this approach and let me know if you need any assistance.. I was not able to test it fully as i don't have any suitable backend that will return the responses, but judging from the RestKit log this should work.

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