通过RestKit将JSON的本地NSString反序列化为对象(无网络下载)

Question

是否可以NSString通过RestKit将JSON 反序列化为对象？我在这里检查了API列表,找不到可以用于此目的的东西.我能找到的最接近的是NSDictionary解析输入后返回的各种解析器类.我假设RestKit在下载响应后使用这些解析器,所以我的想法是RestKit中的某个功能可用,但不公开.

如果我没有遗漏任何东西并且没有公开这个功能,那么替代方案是什么？两个明显的看起来不太有希望:获得结果NSDictionary并尝试反序列化自己(有效地重新实现RestKit)或尝试深入RestKit源并查看是否可以某种方式暴露(看起来单调乏味且容易出错).

在此先感谢您的帮助.

PS:我们的想法是,反序列化对象上的字符串属性实际上是另一组对象的JSON表示(在某种意义上是嵌入式JSON),并且在运行时根据需要进行反序列化.

Answer 1

非常"简单":

NSString *stringJSON;
...

RKJSONParserJSONKit *parser;
NSError *error= nil;
parser= [[[RKJSONParserJSONKit alloc] init] autorelease]; 
MyManagedObject *target;
target= [MyManagedObject object];

NSDictionary *objectAsDictionary;
RKObjectMapper* mapper;
objectAsDictionary= [parser objectFromString:stringJSON error:&error];
mapper = [RKObjectMapper mapperWithObject:objectAsDictionary 
                          mappingProvider:[RKObjectManager sharedManager].mappingProvider];
mapper.targetObject = target;
RKObjectMappingResult* result = [mapper performMapping];
NSLog(@"%@", [result asObject]);

Answer 2

截至RestKit 0.20.0-pre2

NSString* JSONString = @"{ \"name\": \"The name\", \"number\": 12345}";
NSString* MIMEType = @"application/json";
NSError* error;
NSData *data = [JSONString dataUsingEncoding:NSUTF8StringEncoding];
id parsedData = [RKMIMETypeSerialization objectFromData:data MIMEType:MIMEType error:&error];
if (parsedData == nil && error) {
    // Parser error...
}

AppUser *appUser = [[AppUser alloc] init];

NSDictionary *mappingsDictionary = @{ @"someKeyPath": someMapping };
RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData mappingsDictionary:mappingsDictionary];
mapper.targetObject = appUser;
NSError *mappingError = nil;
BOOL isMapped = [mapper execute:&mappingError];
if (isMapped && !mappingError) {
    // Yay! Mapping finished successfully
    NSLog(@"mapper: %@", [mapper representation]);
    NSLog(@"firstname is %@", appUser.firstName);
}

Answer 3

这适用于Restkit 0.21.0:

NSString* jsonFilePath = [[NSBundle mainBundle] pathForResource:@"fileName"
                                                 ofType:@"json"];

NSString* JSONString = [NSString stringWithContentsOfFile:jsonFilePath
                                              encoding:NSUTF8StringEncoding
                                                 error:NULL];


NSError* error;
NSData *data = [JSONString dataUsingEncoding:NSUTF8StringEncoding];
id parsedData = [RKMIMETypeSerialization objectFromData:data MIMEType:RKMIMETypeJSON error:&error];
if (parsedData == nil && error) {
    // Parser error...
}

//_objectManager is RKObjectManager instance
NSMutableDictionary *mappingsDictionary = [[NSMutableDictionary alloc] init];
for (RKResponseDescriptor *descriptor in _objectManager.responseDescriptors) {
    [mappingsDictionary setObject:descriptor.mapping forKey:descriptor.keyPath];
}

RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData mappingsDictionary:mappingsDictionary];
NSError *mappingError = nil;
BOOL isMapped = [mapper execute:&mappingError];
if (isMapped && !mappingError) {
    NSLog(@"result %@",[mapper mappingResult]);
}

Answer 4

这适用于Restkit 0.20,使用核心数据实体.它基于@innerself给出的解决方案

NSString* jsonFilePath = [[NSBundle mainBundle] pathForResource:@"info-base"
                                                         ofType:@"json"];

NSString* JSONString = [NSString stringWithContentsOfFile:jsonFilePath
                                                 encoding:NSUTF8StringEncoding
                                                    error:NULL];


NSError *error = nil;

NSData *data = [JSONString dataUsingEncoding:NSUTF8StringEncoding];
id parsedData = [RKMIMETypeSerialization objectFromData:data MIMEType:RKMIMETypeJSON error:&error];
if (parsedData == nil && error) {
    // Parser error...
    NSLog(@"parse error");
}

//_objectManager is RKObjectManager instance
NSMutableDictionary *mappingsDictionary = [[NSMutableDictionary alloc] init];
for (RKResponseDescriptor *descriptor in [RKObjectManager sharedManager].responseDescriptors) {

    [mappingsDictionary setObject:descriptor.mapping forKey:descriptor.keyPath];
}

RKManagedObjectMappingOperationDataSource *datasource = [[RKManagedObjectMappingOperationDataSource alloc]
                                                         initWithManagedObjectContext:[RKManagedObjectStore defaultStore].persistentStoreManagedObjectContext
                                                                                cache:[RKManagedObjectStore defaultStore].managedObjectCache];

RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData
                                                           mappingsDictionary:mappingsDictionary];
[mapper setMappingOperationDataSource:datasource];

NSError *mappingError = nil;
BOOL isMapped = [mapper execute:&mappingError];
if (isMapped && !mappingError) {
    // data is in [mapper mappingResult]
}