StackOverflow2013

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POObjective-C DRY JSON Mapping and Object Creation
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copied!<p>I am trying to dynamically map JSON information into different objects. But I can't figure out quite how to get the whole pointer situation under control, as what I was hoping would work does not.</p> <p>So far my methodology has been to create a dictionary for each object, mapping the variable pointers to the equivalent JSON keys. In my JSON mapper, I have a method, <code>parseJSONFromDictionary:withObject</code> that is supposed to iterate over the dictionary returned by <a href="http://code.google.com/p/json-framework/" rel="noreferrer">SBJSON</a>'s JSONValue and assign the appropriate values to the appropriate variables in the given object.</p> <pre><code>-(NSObject *)parseJSONFromDictionary:(NSDictionary *)dict withObject:(NSObject *)start{ for (NSString *key in dict) { if ([[self.mappings objectForKey:key] isMemberOfClass:[NSString class]]) { start.[self.mappings objectForKey:key] = [[dict valueForKey:key] stringValue]; } } return start; }</code></pre> <p><code>mappings</code> is the dictionary that has the variables and json keys, and the <code>dict</code> is what gets returned from the json parser.</p> <p>The big problem is that I can't do <code>start.[self.mappings objectForKey:key]</code>. I don't know much about C, and clearly I don't know enough about pointers, so how would I go about creating this kind of system? I know that's not the right way to do this, but what is the right way? I know it can be done, as <a href="http://restkit.org" rel="noreferrer">RestKit</a> does it, but they don't support OAuth so I sadly can't use their lovely framework.</p> <p>The reason I'm going this route is because the API I'm working with is currently in its alpha stage. I want to be able to easily adapt to any future changes without having to rewrite many lines of code. I also want to start programming DRY-ly. I know JSON parsing is very repetitive, and I'd like to find a way to reduce the amount of overhead.</p> <p>Thanks for any and all help!</p> <hr> <p><strong>EDIT:</strong> It seems there is some confusion as to what I'm asking. I <em>do not</em> need help parsing JSON. I'm using <a href="http://code.google.com/p/json-framework/" rel="noreferrer">SBJSON</a> already. I <em>do not</em> need help making requests, I am already using <a href="https://github.com/jdg/oauthconsumer" rel="noreferrer">JDG's OAuthConsumer framework</a>. I <em>can only</em> use frameworks that support OAuth 2.0.</p> <p><em>I do need help</em> figuring out how to <strong>prevent</strong> this:</p> <pre><code>-(Class1 *)parseJsonForClass1:(NSString *)inputString { NSDictionary *outputDict = [inputString JSONValue]; Class1 *instance1 = [self mapObjectsForClass1From:outputDict]; return instance1; } -(Class2 *)parseJsonForClass2:(NSString *)inputString { NSDictionary *outputDict = [inputString JSONValue]; Class2 *instance2 = [self mapObjectsForClass2From:outputDict]; return instance2; } -(Class3 *)parseJsonForClass3:(NSString *)inputString { NSDictionary *outputDict = [inputString JSONValue]; Class2 *instance3 = [self mapObjectsForClass3From:outputDict]; return instance3; } -(Class1 *)mapObjectsForClass1From:(NSDictionary *)dict { Class1 *object1 = [[Class1 alloc] init]; object1.name = [[dict valueForKey:@"name"] stringValue]; object1.date = [[dict valueForKey:@"date"] stringValue]; object1.objId = [[dict valueForKey:@"id"] intValue]; return object1; } -(Class2 *)mapObjectsForClass2From:(NSDictionary *)dict { Class2 *object2 = [[Class2 alloc] init]; object2.something = [[dict valueForKey:@"something"] stringValue]; object2.title = [[dict valueForKey:@"title"] stringValue]; object2.imageUrl = [[dict valueForKey:@"image_url"] stringValue]; return object2; } -(Class3 *)mapObjectsForClass3From:(NSDictionary *)dict { Class3 *object3 = [[Class3 alloc] init]; object3.foo = [[dict valueForKey:@"bar"] stringValue]; object3.flag = [[dict valueForKey:@"is_member"] boolValue]; object3.obj1 = [[Class1 alloc] init]; object3.obj1 = [self mapOjectsForClass1From:[dict objectForKey:@"name1"]]; return object3; }</code></pre> <p>So please let me know if you have any suggestions on how to combine these kinds of methods into 1 method...</p>

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