Using JSON Framework on iPhone - HELP!

问题

Currently I am using the following code to parse the JSON link sent. This is how I also send a GET call to the Google Reader API for an upcoming iPhone application of mine.

- (NSArray *)subscriptionList
{
if(!cookies && [cookies count] == 0) {
    [self requestSession];
}

NSString * url = @"http://www.google.com/reader/api/0/subscription/list?output=json&client=scroll";

ASIHTTPRequest * request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:url]];
[request setRequestMethod:@"GET"];
[request setRequestCookies:cookies];
[request addRequestHeader:@"Authorization" value:[NSString stringWithFormat:@"GoogleLogin auth=%@", [self auth]]];

[request startSynchronous];

subfeeds = [NSMutableArray array];

// Create new SBJSON parser object
SBJSON *parser = [[SBJSON alloc] init];

if ([request responseStatusCode] == 200) {

    NSData * sixty = [request responseData];

    NSString * body = [[NSString alloc] initWithData:sixty encoding:NSUTF8StringEncoding];
    if (body) {
        NSArray *feeds = [parser objectWithString:body error:nil];
        NSLog(@"Array Contents: %@", [feeds valueForKey:@"subscriptions"]);
        NSLog(@"Array Count: %d", [feeds count]);

        NSDictionary *results = [body JSONValue];
        NSArray *ohhai = [results valueForKey:@"subscriptions"];

        for (NSDictionary *title in ohhai) {
            subTitles = [title objectForKey:@"title"];
            NSLog(@"title is: %@",subTitles);
        }
    }
}

return subfeeds;
[subTitles release];
[parser release];
}

I can successfully parse the JSON using the above code, and it successfully outputs the titles into NSLog. In my RootViewController.m, I call the following to grab this -(NSArray *)subscriptionList.

-(void)viewDidAppear:animated {
GoogleReader * reader = [[GoogleReader alloc] init];
[reader setEmail:gUserString];
[reader setPassword:gPassString];

//feedItems is a NSArray where we store the subscriptionList NSArray
feedItems = [reader subscriptionList];

//NSString *feedTitle = [];

NSLog(@"%@", feedItems);

[reader release];
// the rest of the function
}

The code above successfully works with the credentials entered. As you can see there is also a commented NSString called feedTitle. This is where I want to pull the @"title" from the parsed JSON but I do not know how to call it.

Any help would be greatly appreciated!

This is what the JSON source looks like:

{"subscriptions":
[
{"id":"","title":"","categories":[],"sortid":"","firstitemmsec":""},
{"id":"","title":"","categories":[],"sortid":"","firstitemmsec":""},
{"id":"","title":"","categories":[],"sortid":"","firstitemmsec":""},
{"id":"","title":"","categories":[],"sortid":"","firstitemmsec":""},
{"id":"","title":"","categories":[],"sortid":"","firstitemmsec":""}
]
}

I'm interested in only the "title" node.

回答1:

Well, it would help if you added the source JSON but it's quite easy to grasp how SBJSON parses incoming JSON.

Just an example:

{ "myOutDict" : { "key1": "val1" , "key2" : "val2"} }

This JSON String would be parsed so you can access it by using this code

NSDictionary* myOuterdict = [feeds valueForKey:@"myOutDict"]);
NSString* val1 =  [myOuterdict valueForKey:@"key1"]);
NSString* val2 =  [myOuterdict valueForKey:@"key2"]);

Edit: Checked my personal Google Reader feed:

The JSON looks like this

{
    "subscriptions": [{
        "id": "feed/http://adambosworth.net/feed/",
        "title": "Adam Bosworth's Weblog",
        "categories": [],
        "sortid": "0B5B845E",
        "firstitemmsec": "1243627042599"
    },
    {
        "id": "feed/http://feeds.feedburner.com/zukunftia2",
        "title": "Zukunftia",
        "categories": [],
        "sortid": "FCABF5D4",
        "firstitemmsec": "1266748722471"
    }]
}

So the corresponding Objective C Code would be:

NSArray* subscriptions= [feeds valueForKey:@"subscriptions"]);
foreach(NSDictionary* item in subscriptions) {
    // Do stuff 
    // NSString* title = [item valueForKey:@"title"]
    // NSString* id = [item valueForKey:@"id"]
}

回答2:

I'm not sure I understand the question. Are you trying to get a title for the feed as a whole, or per-item? Because I can't see a title property for the subscriptions array in the source JSON.

来源：https://stackoverflow.com/questions/3836445/using-json-framework-on-iphone-help

标签

iphone

objective-c

nsarray

google-reader

json-framework