Parsing JSON ( again ) in iOS - iphone

Question

I'm just playing with the JSON parser in iOS it's working fine as a ( simple ) example . But I was wonder how one would actually parse something (a bit) more complicated, the a Twitter trends JSON, like this :
{
"trends": {
"2011-03-13 11:42:17": [
{
"events": null,
"query": "Fukushima",
"promoted_content": null,
"name": "Fukushima"
},
{
"events": null,
"query": "Rebecca Black",
"promoted_content": null,
"name": "Rebecca Black"
},
{
"events": null,
"query": "Pearl Harbour",
"promoted_content": null,
"name": "Pearl Harbour"
},
...
{
"events": null,
"query": "Magdalena Neuner",
"promoted_content": null,
"name": "Magdalena Neuner"
}
]
},
"as_of": 1300016537
}
How would one just return the first 3 queries ? in this instance : Fukushima, Rebecca Black and Pearl Harbour .
Using the example code, it goes something like this :
for (int i = 0; i < [luckyNumbers count]; i++)
[text appendFormat:#"%#\n", [luckyNumbers objectAtIndex:i]];
This is for a much simpler feed though, can it be approached the same way for what I'm looking for ?
I'm trying to return the value of "query":
So I`m doing this :
NSLog(#"%#", [[luckyNumbers objectForKey:#"trends"]);
This of course logs the content of the key "trend", how do I go about returning not only the first ( and only ) key of trends but also dig one more level down to return the content of "query" ??
I've also tried something like this :
NSString *date = [[[luckyNumbers valueForKeyPath:#"trends"] allKeys] description];
NSArray *trends = [luckyNumbers objectForKey:#"trends"];
NSLog(#"%#", [trends valueForKeyPath:date]);
but no go ...
EDIT (aftet honcheng's answer):
Because I want to iterate through the results of "trends", I'm doing :
NSDictionary *luckyNumbers = [responseString JSONValue];
NSArray *keys = [[luckyNumbers objectForKey:#"trends"] allKeys];
for (int i =0; i < [keys count]; i++) {
NSLog(#"%#", [keys objectAtIndex:i]);
}
Obviously something is wrong because I'm not getting any result ..

Answer 1

JSON parser usually returns native NSObjects such as NSDictionary and NSArray. After parsing, you just have to treat it like a new object.
[luckyNumbers allKeys] returns an NSArray ["trends", "as_of"]
[[luckyNumbers objectForKey:#"trends"] allKeys"] returns an NSArray ["2011-03-13 11:42:17"]
Since allKeys returns an NSArray, you can just use a for loop to get all your keys.