AFNetworking - Build NSDictionary parameters - iphone

Question

I'm trying to build my NSDictionnary to send to a request using the AFNetworking framework, but it seems that I'm quite confused about how to do it properly.
Here's what the server is expecting :
{
"limit":10,
"filters":
[
{"field":"owner","operator":"EQUAL","value":"ownerId","type":"integer"},
{"field":"date","operator":"GE","value":"30 Jun 2010 00:00:00","type":"date"},
],
"order":[{"field":"date","order":"ASC"}],
"page":0
}
What I'm trying to do (I don't really know if it's the right way to do it tbh), is to build a NSDictionary like the following :
NSDictionary *parameters = [NSDictionary dictionaryWithObjectsAndKeys:
#"10", #"chunkSize",
[NSDictionary dictionaryWithObjectsAndKeys:
[NSDictionary dictionaryWithObjectsAndKeys:#"owner", #"field", #"EQUAL", #"operator", #"ownerId", #"value", #"integer", #"type", nil],
[NSDictionary dictionaryWithObjectsAndKeys:#"date", #"field", #"GE", #"operator", #"30 Jun 2010 00:00:00", #"value", #"date", #"type", nil],
nil], #"filters",
[NSDictionary dictionaryWithObjectsAndKeys:
[NSDictionary dictionaryWithObjectsAndKeys:#"date", #"field", #"ASC", #"order", nil],
nil], #"order",
#"0", #"page",
nil];
But I have the following error when the view is loading :
*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '+[NSDictionary dictionaryWithObjectsAndKeys:]: second object of each pair must be non-nil
I know I screw up building the parameters properly, but I can't manage to do it after several tries. Could anyone help ? Moreover, I don't really know the differences that I must implement here with the [] and the {}. I read that {} was for a dictionary and [] for an array, but I don't really see how to translate it in my case.

Answer 1

Your mistake is that the value for the dictionary starting on line 3 needs to be wrapped in an array.
At least until Objective-C array and hash literals go mainstream, my preferred method for creating complex dictionaries is to build them from an NSMutableDictionary. In your case:
NSMutableDictionary *mutableParameters = [NSMutableDictionary dictionary];
[mutableParameters setValue:#"10" forKey:#"limit"];
// ...
NSMutableArray *mutableFilters = [NSMutableArray array];
NSMutableDictionary *mutableOwnerFilterDictionary = [NSMutableDictionary dictionary];
[mutableOwnerFilterDictionary setValue:#"owner" forKey:#"field"];
// ...
[mutableFilters addObject:mutableOwnerFilterDictionary];
[mutableParameters setValue:mutableFilters forKey:#"filters"];
// ...
Also, be sure you're sending that over as JSON by setting AFJSONParameterEncoding to your AFHTTPClient.

Answer 2

The brackets [] signify an array, while the braces {} signify an object (dictionary in this context). To produce the structure you require:
NSDictionary *parameters = [NSDictionary dictionaryWithObjectsAndKeys:
#"10", #"chunkSize",
[NSArray arrayWithObjects:
[NSDictionary dictionaryWithObjectsAndKeys:#"owner", #"field", #"EQUAL", #"operator", #"ownerId", #"value", #"integer", #"type", nil],
[NSDictionary dictionaryWithObjectsAndKeys:#"date", #"field", #"GE", #"operator", #"30 Jun 2010 00:00:00", #"value", #"date", #"type", nil],
nil], #"filters",
[NSArray arrayWithObjects:
[NSDictionary dictionaryWithObjectsAndKeys:#"date", #"field", #"ASC", #"order", nil],
nil], #"order",
#"0", #"page",
nil];