i'm new in the iphone and json world . i have this json structure . You can see it clearly by putting it here http://jsonviewer.stack.hu/ .
{"#uri":"http://localhost:8080/RESTful/resources/prom/","promotion":[{"#uri":"http://localhost:8080/RESTful/resources/prom/1/","descrip":"description
here","keyid":"1","name":"The first
name bla bla
","url":"http://localhost/10.png"},{"#uri":"http://localhost:8080/RESTful/resources/promo/2/","descrip":"description
here","keyid":"2","name":"hello","url":"http://localhost/11.png"}]}
i want to parse it with json-framework . I tried this
NSDictionary *json = [myJSON JSONValue];
NSDictionary *promotionDic = [json objectForKey:#"promotion"];
NSLog(#" res %# : ",[promotionDic objectAtIndex:0]);
But then how to do to get for exemple , the name of the object at index 0 ? I think i should put object in an NSArray ? but i dont find how :/ and i dont the number of object is variable . Help please .
First off, You need this line after you load the JSON
NSLog(#" json %# : ",[json description]);
That will tell you what you have.
Secondly, you can't call objectAtIndex: on a dictionary. If it works, its because promotionDict is really an NSArray. (The NSLog will tell you). In Objective - C you can assign to any kind of pointer, which is confusing to new developers, but is part of the language, and really is a feature.
With an NSArray you can ask for the number of things in it, [myArray count], etc. You need to command double click in XCode to open up the docs for NSDictionary, etc.
The JSON says:
..."promotion":[{"#u...
That "[" there means that "promotion" is keyed to an array, not a dictionary.
So really your code should be:
NSDictionary *json = [myJSON JSONValue];
NSArray *promotions = [json objectForKey:#"promotion"];
NSLog(#"res: %#",[promotions objectAtIndex:0]);
Related
I'm stuck at json object parsing really tried hard. The problem is how to parse the json object. Here's what i get the response in the log.
{"0":{"**title**":"Test Event","url_title":"test_event1","status":"open","entry_date":"Sep 10, 2012,
05:20:38AM","entry_id":"26","site_id":"1","channel_id":"3","field_dt_40":null,"field_dt_58":null,"channel_title":"News &
Events","channel_name":"news_events","start_date":"1348120800","end_date":"1348120800","start_time": "43200","end_time":"46800","where":"FCF","news_event_description":"<p>\n\tLunch with group.<\/p>\n"},
"1":{"**title**":"Test Event 2","url_title":"test_event_2","status":"open","entry_date":"Sep 10, 2012, 05:20:08AM","entry_id":"28","site_id":"1","channel_id":"3","field_dt_40":null,"field_dt_58":null,"channel_title":"News & Events","channel_name":"news_events","start_date":"1348207200","end_date":"1348207200","start_time":"43200","end_time":"46800","where":"FCF - Lunch","news_event_description":"<p>\n\tThis was a great event.<\/p>\n"},
"2":{"**title**":"Test Event 3","url_title":"test_event_3","status":"open","entry_date":"Sep 10, 2012, 05:20:54AM","entry_id":"29","site_id":"1","channel_id":"3","field_dt_40":null,"field_dt_58":null,"channel_title":"News & Events","channel_name":"news_events","start_date":"1346738400","end_date":"1346738400","start_time":"7200","end_time":"11700","where":"FCF - Lunch","news_event_description":"<p>\n\tFall planning season.<\/p>\n"}}
The problem is i want to show all the titles in the tableview. I can get the single Title by using key 0,1,2. But i want all the titles to be shown at once i parse
Please help me out guys, Thanks in advance.
Suppose jsonDict is your json dictionary.... Try this
NSArray * keys=[[NSArray alloc]init];
keys=[jsonDict allKeys];
NSMutableArray *titles=[[NSMutableArray alloc]init];
for(int i=0;i<[keys count];i++){
[titles addObject:[[jsonDict valueForKey:[keys objectAtIndex:i]]valueForKey:#"title"]];
}
NSLog(#"your array of titles : %#",titles); //use this array to fill your cell
Are you trying to parse the JSON yourself? You might find it easier to use something that's already well tested, such as TouchJSON or Apple's own NSJSONSerilization. The result should be a graph of Objective-C objects that you can use however you like.
In any case, what you've got there is the equivalent of a dictionary of dictionaries. If you have that as a NSDictionary called myJSONDictionary, you can say:
NSArray *theObjects = [myJSONDictionary allValues]; // gets all the objects
NSArray *theTitles = [theObjects valueForKey:#"**title**"]; // gets all the titles
You can also iterate through a dictionary using fast enumeration:
NSMutableArray *theTitles = [NSMutableArray array];
for (NSString *key in myJSONDictionary) {
NSDictionary *object = [myJSONDictionary objectForKey:key];
NSString *title = [object objectForKey:#"**title**"];
[theTitles addObject:title]
}
There's no real advantage to doing that instead of using KVC as in the first example if you just need the titles, but it could be the right choice if you have more complex work to do for each object.
Hey guys :) I am quite new to stack overflow and iPhone programming. I am trying to parse a complex JSON to display some stuff in the UITableView.
a part of the JSON structure -
{"1":{"1":"Ent1","done":"No"},"2":{"1":"Ent2","done":"No"}}
I am able to parse through the main keys "1" and "2" and able to grab the values corresponding to the key "1" inside {"1":"Ent1","done":"No"}, {"1":"Ent2","done":"No"} store them into a dictionary/ a string with the following code :
for (NSString *key in dict)
{
NSString *answer = [dict objectForKey:#"1"];
NSLog(#"%#", answer);
}
The result is Ent1 and Ent2 because the code iterates over the for loop and checks for the objects with key "1".
The problem is this - I want to store both the values(Ent1 and Ent2) into an array.
I use the following code:
NSMutableArray *array = [[NSMutableArray alloc] initWithObjects: answer, nil];
but it just takes the last index in the dictionary which is Ent2.
Could you please tell me how could I add both the values for key 1 into an array?
Thanks in advance :)
To add to jamapag's answer, you can also use JSON libraries in objective C which do all the work for you like SBJSON or YAJL, or even as part of the more recent versions of the mac/iOS SDKs, NSJSONSerialization.
NSMutableArray *array = [[NSMutableArray alloc] init];
for (NSString *key in dict)
{
NSString *answer = [dict objectForKey:key];
[array addObject:answer];
}
I'm using TouchJSON to parse the output of a JSON Rails API, but am having difficulties. The overall goal is to loop through the response, parse the JSON, create a Round instance for each JSON object, and stick those Round objects into an NSArray so I can load this into a UITableView. So if there's a more straight-forward way to do that than what I'm about to show (which currently is NOT working, btw) please let me know.
The Rails API is returning a collection that looks something like this:
[
{
"round": { "course_title": "Title A", "result": "+8" }
},
{
"round": { "course_title": "Title B", "result": "+4" }
},
...
]
I'm also using ASIHTTPRequest and I can successfully get the response using:
NSString *responseString = [request responseString];
But from there, I cannot seem to get anywhere. Here's more-or-less what TouchJSON suggests:
NSString *jsonString = [request responseString]; // [{"round":{...}}, ..., {"round:{...}}]
NSData *jsonData = [jsonString dataUsingEncoding:NSUTF32BigEndianStringEncoding];
NSDictionary *dictionary = [[CJSONDeserializer deserializer] deserializeAsDictionary:jsonData error:nil];
// then I do this...
NSLog(#"JSON: %#", dictionary); // JSON: null
I thought from there I would be able to loop through the dictionary and create the object mappings using my Round class. But maybe that's the wrong approach altogether.
My thoughts are that the JSON being returned from Rails is an array of JSON objects, so maybe that's why the JSON parser doesn't recognize it as valid JSON? From this, I have two questions:
1) Should TouchJSON be able to accept an array of JSON objects like what my API is returning?
2) Is it possible to cast the responseString to an NSArray so I can loop through each "round" and parse the JSON that way? If I remove the first and last characters from the response string (i.e. "[" and "]") the JSON parser will only grab the first "round" in the collection.
3) Am I going about this whole process correctly?
Any tips/advice would be much appreciated.
TouchJSON presents three main ways to go from JSON to an Obj-C object. They are all present in the header for CJSONDeserializer which you're already using:
- (id)deserialize:(NSData *)inData error:(NSError **)outError;
- (id)deserializeAsDictionary:(NSData *)inData error:(NSError **)outError;
- (id)deserializeAsArray:(NSData *)inData error:(NSError **)outError;
The first one will return return whatever, either a dictionary, array, string or whatever the root type of the JSON is.
The other two expect a dictionary or an array and will complain (i.e. return nil and give you an NSError) if they don't get the right data.
The deserializeAsDictionary:error: method of CJSONDeserializer relies on the scanJSONDictionary:error: method of CJSONScanner. This method expects the "dictionary" to be an object literal. Therefore, your data must start with a {. Since your data is an array, you would want to use the deserializeAsArray:error: method of CJSONDeserializer.
Read the documentation carefully, your code is incorrect. It should look like this:
NSData *jsonData = [request responseData]
NSArray *rounds = [[CJSONDeserializer deserializer] deserialize:jsonData error:nil];
// then I do this...
NSLog(#"JSON: %#", rounds);
You could also have used:
NSArray *rounds = [[CJSONDeserializer deserializer] deserializeAsArray:jsonData error:nil];
However your absolute BIGGEST mistake was passing nil for error. You could have avoided going to stackoverflow at ALL if you had passed something in for NSError and then checked that.
With the right tools, this is WAY simpler than you're making it. I do this sort of thing all the time.
Use Stig's JSON framework, and import the NSString category that provides the JSONValue method.
Then inside your ASIHTTPRequest response handler code, go thusly:
NSMutableArray *roundlist = [NSMutableArray array];
NSArray *results = [[request responseString] JSONValue];
for (NSDictionary *item in results) {
Round *myRound = [item objectForKey:#"round"];
//don't actually do the above. Do whatever you do to instantiate a 'Round'.
[roundlist addObject:myRound];
}
[self.tableView reloadData];
EDIT: Geezo. Objection noted re valueForKey: vs objectForKey:. I updated my code sample, and I think we all learned something here.
I also didn't mean any offense with the phrase "with the right tools". OP was looking to simplify his code, and the RIGHT TOOL for that is the library with the simplest interface. I have nothing against TouchJSON per se, but JSON Framework has the simpler interface.
NSDictionary *story = [stories objectAtIndex: indexPath.row];
cell.text=[NSString stringwithFormat:[story objectForKey#"message];
i dont knw what exaclty "message " contains (what is the meaning of objectForKey#"message")
EDIT CODE
NSString *key =[appDelegate.books objectAtIndex:indexPath.row];
//dict y=#"Name";
NSArray *nameSection = [dict objectForKey:key];
NSDictionary *story = [nameSection objectAtIndex: indexPath.row];
cell.text=[NSString stringwithFormat:[story objectForKey:key]];
NSLog(#"Value Of message: %#", [dict objectForKey:key]);
why my code crashes
If you are more familiar with Java or C# the code is equivalent to something like this:
// Assuming stories is declared as: List<Dictionary<string, string> stories;
Dictionary<string, string> story = stories[indexPath.row];
cell.Text = String.Format(story["message"]);
In Smalltalk-style (and therefore Objective-C too) Object Oriented programming, methods are more like messages to other objects. So a good Objective-C method name should read like an English sentence (Subject-Verb-Object). Because of this working with dictionaries (hash tables) looks like this:
[myDictionary setObject:#"Value" forKey:#"someKey"];
[myDictionary objectForKey:#"someKey"]; // == #"Value"
In Java it would be:
myDictionary.put("someKey", "Value");
myDictionary.get("someKey"); // == "Value"
Notice how the key ("someKey") was the first argument in the Java example. In Objective-C you name your arguments with the method name, hence setObject: forKey:. Also notice that in Objective-C strings start with an # symbol. That's because Objective-C strings are different from regular C strings. When using Objective-C you almost always use Objective-C's # strings.
In C# there is a special syntax for Dictionaries so it becomes:
myDictionary["someKey"] = "Value";
myDictionary["someKey"]; // == "Value"
One important problem that you might encounter if you're new is the problem of native types.
In Java to add an int to a Dictionary you used to have to do:
myDictionary.put("someKey", new Integer(10));
Because the primitive types (int, char/short, byte, boolean) aren't real Objects. Objective-C has this problem too. So if you want to put an int into a dictionary you must use NSNumber like so:
[myDictionary setObject:[NSNumber numberForInt:10]
forKey:#"someKey"];
And you pull out the integer like so:
NSNumber *number = [myDictionary objectForKey:#"someKey"];
[number intValue]; // == 10
EDIT:
Your code might be crashing if you have a '%' character in your string, since stringWithFormat is just like NSLog in that it takes many arguments. So if story["message"] is "Hello" then it'll work fine without extra arguments but if it's "Hello %#" you need to add one argument to stringWithFormat.
NSString *message = #"Hello %#";
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
[dict setObject:message forKey:#"message"];
NSString *output = [NSString stringWithFormat:[dict objectForKey:#"message"], #"World!"];
// output is now #"Hello World!".
#"message" is a key for a value stored in the NSDictionary object. The first line declares an NSDictionary named story that appears to come from an array.
If you want to find what value is stored for the key:#"message", consider using:
NSLog(#"Value Of message: %#", cell.text);
Run and check the console to see the output. (SHIFT + COMMAND + Y) in XCode will bring up the console, if that's what you are using. If you are unfamiliar with NSArrays/NSDictionaries, give Apple's Documentation a look.
I'm just guessing at all of this since that is a very limited sample of code. Try submit more code when you ask a question so that the viewers can get a better idea of your questions.
That is an example of key-value coding, and a lot of information is available on the Apple dev site if you're interested:
http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/KeyValueCoding/KeyValueCoding.html
example 1: ==> [{"name":"luxy"}]
example 2: ==> {"name":"luxy"}
Both example I got are valid json format...
in xcode... I write below:
[dictionary objectForKey:#"name"]
in example 2 I can get "luxy" but how come if I use example 1 then it fails?
is my xcode wrong?
I'm guessing that you're using stig's json-framework? If so, when you parse example one you get an NSArray. When you parse example two, you get an NSDictionary.
id example1 = [parser objectWithString:jsonString];
if ([example1 isKindOfClass:[NSArray class]]) {
// You've got an array, probably an array of dictionaries
} else if ([example1 isKindOfClass:[NSDictionary class]]) {
// you've got a dictionary, handle it
} else {
// you've got something else
}
Thanks to Kubi!!! You are right! forgot the basic json logic about array & object difference...
I am quite new into xcode but kinda of weird....
if is array ...
NSString *element = [example1 objectAtIndex:0];
I can get the string from element... but weird when I put
NSDictionary *dictionary = [element JSONValue]; <== at this stage I get some unrecongized selector.....
[dictionary objectForKey:#"name"]