A concise Mantle-like way of working with Realm and JSON.
Add the following to your CocoaPods Podfile
pod 'Realm+JSON', '~> 0.1'
or clone as a git submodule,
or just copy files in the Realm+JSON folder into your project.
Simply declare your model as normal:
typedef NS_ENUM(NSInteger, MCEpisodeType) {
MCEpisodeTypeFree = 0,
MCEpisodeTypePaid
};
@interface MCEpisode : RLMObject
@property NSInteger episodeID;
@property NSInteger episodeNumber;
@property MCEpisodeType episodeType;
@property NSString *title;
@property NSString *subtitle;
@property NSString *thumbnailURL;
@property NSDate *publishedDate;
@end
RLM_ARRAY_TYPE(MCEpisode)
Then pass the result of NSJSONSerialization or AFNetworking as follows:
[MCEpisode createInRealm:[RLMRealm defaultRealm] withJSONArray:array];
or
[MCEpisode createInRealm:[RLMRealm defaultRealm] withJSONDictionary:dictionary];
When you specify a primaryKey (see below), objects in the realm with same primary key value will be replaced instead of a duplicate version of the object added.
Use the -JSONDictionary method to get a JSON-ready dictionary for your network requests.
You should specify the inbound and outbound JSON mapping on your RLMObject subclass like this:
+ (NSDictionary *)JSONInboundMappingDictionary {
return @{
@"episode.title": @"title",
@"episode.description": @"subtitle",
@"episode.id": @"episodeID",
@"episode.episode_number": @"episodeNumber",
@"episode.episode_type": @"episodeType",
@"episode.thumbnail_url": @"thumbnailURL",
@"episode.published_at": @"publishedDate",
};
}
+ (NSDictionary *)JSONOutboundMappingDictionary {
return @{
@"title": @"title",
@"subtitle": @"episode.description",
@"episodeID": @"id",
@"episodeNumber": @"episode.number",
@"publishedDate": @"published_at",
};
}
Leaving out either one of the above will result in a mapping that assumes camelCase for your properties which map to snake_case for the JSON equivalents.
Specify the primary key property like this:
+ (NSString *)primaryKey {
return @"episodeID";
}
As you can do with Mantle, you can specify NSValueTransformers for your properties:
+ (NSValueTransformer *)episodeTypeJSONTransformer {
return [MCJSONValueTransformer valueTransformerWithMappingDictionary:@{
@"free": @(MCEpisodeTypeFree),
@"paid": @(MCEpisodeTypePaid)
}];
}
Realm requires that you use different RLMRealm objects when working across different threads. This means you shouldn't access the same RLMObject instances from different threads. To make this easier to work with, use - primaryKeyValue to retrieve the wrapped primary key value from an instance and query for it later using + objectInRealm:withPrimaryKeyValue:.
id primaryKeyValue = [episode primaryKeyValue];
dispatch_async(dispatch_get_main_queue(), ^{
MCEpisode *episode = [MCEpisode objectInRealm:[RLMRealm defaultRealm] withPrimaryKeyValue:primaryKeyValue];
// do something with episode here
});
If you need to display UI that may or may not change an object's properties, it is sometimes useful to work with an object not bound to a realm as a backing model object. When it is time to commit changes, the properties can be copied back to the stored model.
Methods - shallowCopy and - mergePropertiesFromObject: are provided. The later of which needs to be performed in a realm transaction.
#import <Realm+Copying.h>
MCEpisode *anotherEpisode = [episode shallowCopy];
anotherEpisode.title = @"New title";
// ...
[episode performInTransaction:^{
[episode mergePropertiesFromObject:anotherEpisode];
}];
Realm+JSON is under the MIT license.