How to set up NSDictionary to be used in Restkit POST request - ios

Question

I have an iOS app that is using RestKit and CoreData. I have run into a road block with making a POST request because the request body is formed from a NSDictionary. The problem I have is the request body needs to have duplicate keys. NSDictionary requires unique keys so I'm not sure how to make this work.
Here is how the server is expecting the request body.
<node>
<personId>2</personId>
<status>2</status>
<title>Dinosaur unearthed somewhere out there. </title>
<point>
<city>Somewhere</city>
<copy><![CDATA[An amazing discovery was unearthed as a local farmer was plowing his field]]></copy>
<state>Outthere</state>
<sequence>1</sequence>
</point>
<point>
<city>Somwhere</city>
<copy><![CDATA[Archeologists from around the world are amazed at the pristine condition of the remains. Also of note is that the farmer was only using a single blade plow on his John Deere tractor when it was unearthed. ]]></copy>
<sequence>2</sequence>
<state>Outthere</state>
</point>
<point>
......
</point>
</node>
This is a simplified version of how I tried to make it work....
params = [[NSMutableDictionary alloc] init];
nodes = [[NSMutableDictionary alloc] init];
nodeParams = [[NSMutableDictionary alloc] init];
NSString *personId = #"2";
NSString *status = #"2";
NSString *title = #"Dinosaur unearthed somewhere out there.";
NSString *city = #"Somewhere";
NSString *state = #"OutThere";
NSString *copyField = #"Testing this out to see if it works";
//Here I set up the point layer of the request body
//In my code this three line section is in a loop. Obviously this does not work because it just overwrites the objectForKey each time through the loop.
[params setObject:copyField forKey:#"copy"];
[params setObject:city forKey:#"city"];
[params setObject:state forKey:#"state"];
//Here I Set up the Node Layer of the request body
[nodeParams setObject:params forKey:#"point"];
[nodeParams setObject:personId forKey:#"personId"];
[nodeParams setObject:status forKey:#"status"];
[nodeParams setObject:title forKey:#"title"];
[nodes setObject:nodeParams forKey:#"node"];
NSLog(#"The Dictionary is %#",nodes);
At runtime the log shows that the body is formatted properly except their is only one point layer and it is populated with the data from the final pass in the loop. Does anyone know of any trickery to get around this?
As a note I believe the postObject method requires the NSDictionary because it passes the dictionary to a JSON Serialization tool. I suspect the serialization tool is expecting a dictionary to be passed in. If someone knows otherwise correct me if I'm wrong.

Answer 1

Okay I finally figured this out. It wasn't until I converted the XML above into JSON that I realized how it could be done. The key is recognizing how an Array and NSDictionary are formatted in the 'NSJSONSerialization' class.
Here is an example of how the server was expecting the JSON.
{ "status":"2",
"title":"test #5",
"personId":"1",
"point":[
{ "copy":"<p class=\"pt\" data-seq=\"1\">This is paragraph #1<\/p>",
"state":"OutThere",
"city":"Somewhere",
"sequence":"1"
},
{ "copy":"<p class=\"pt\" data-seq=\"2\">This is paragraph #2<\/p>",
"state":"OutThere",
"city":"Somewhere",
"sequence":"2"
}
]
}
The critical thing to note here is that the "point" field is and Array of Dictionaries. The [ denotes an array. Once I finally clued in on that I realized that each time through the loop I could reinitialize my dictionary, add the new objects, and then add the current dictionary to the array as you can see below.
while (![theScanner isAtEnd]) {
count = count +1;
//Initialize the dictionary
points = [[NSMutableDictionary alloc] init];
NSString *htmlTag = [NSString stringWithFormat:#"<p class=\"pt\" data-seq=\"%d\">",count];
[theScanner scanUpToCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:&temp];
NSString *preTagText = [htmlTag stringByAppendingString:temp];
NSString *postTagText = [preTagText stringByAppendingString:#"</p>"];
NSString *sequence = [NSString stringWithFormat:#"%d",count];
[points setObject:postTagText forKey:#"copy"];
[points setObject:sequence forKey:#"sequence"];
[points setObject:city forKey:#"city"];
[points setObject:state forKey:#"state"];
[pointArray addObject:points];
points = nil;
}
[params setObject:titleText forKey:#"title"];
[params setObject:personIdNumber forKey:#"personId"];
[params setObject:status forKey:#"status"];
[params setObject:pointArray forKey:#"point"];
After the loop is finished I just add the pointArray to the dictionary as the object with the key point (Thanks Wain). I add the title, status, and personId objects to the same dictionary and use it as the NSDictionary required for the Restkit POST request.