Reading Json

[Scrooby]

Hi All,

I'm new to obj-c and trying to build my first app. I'm trying to parse some Json from a web service like the following format:

{
    "data": {
        "2010-12": {
            "category1": {
                "rate": "xx", 
                "level": "xx", 
                "total": "xx"
            }, 
            "category2": {
                "rate": "xx", 
                "level": "xx", 
                "total": "xx"
            }
        },
        "2011-01": {
            "category1": {
                "rate": "xx", 
                "level": "xx", 
                "total": "xx"
            }, 
            "category2": {
                "rate": "xx", 
                "level": "xx", 
                "total": "xx"
            }
        }
    }
}

I've started writing the following in the connectionDidFinishLoading but from here I'm getting stuck:

NSString *content = [[NSString alloc] initWithBytes:[responseData bytes] length:[responseData length] encoding:NSUTF8StringEncoding];
	
SBJSON *parser = [[SBJSON alloc] init];
NSDictionary *json = [parser objectWithString:content error:nil];
NSArray *months = [json objectForKey:@"data"];
	
for(NSDictionary *month in months){

}
	
[parser release];

Ideally my end result would be an NSArray of objects with each "category", "level", "rate" and "total" being properties of the object.

Any help with this would be much appreciated.

Thanks in advanced.

Scrooby

[smasher]

Judging from your JSON you don't have any arrays - everything appears to be a dictionary - so this line is wrong:

NSArray *months = [json objectForKey:@"data"];

The "months" variable is a dictionary. This would work:

NSDictionary *monthDict = [json objectForKey:@"data"];

Now you need to loop each key for that dictionary and create the objects you need.

for(NSDictionary *dateKey in monthDict){
     //dateKey contains "2010-12"
     NSDitionary *monthValues = [monthDict objectForKey:dateKey]; 
     Month *month = [[Month alloc] initWithdate:dateKey dictionary:monthValues];
     [objectArray addObject:month];
     [month release];
}

You'll need to create the Month class yourself, and decide if it keeps an array of categories or if it always has category1 and category2 properties or what.

[Scrooby]

That's a great help, much appreciated! I could do with a push in the right direction for the initWithDate method.

My end results needs to be an array of categories as the names of the could change.

for(NSDictionary *dateKey in monthDict){
     //dateKey contains "2010-12"
     NSDitionary *monthValues = [monthDict objectForKey:dateKey]; 
     Month *month = [[Month alloc] initWithdate:dateKey dictionary:monthValues];
     [objectArray addObject:month];
     [month release];
}

So based on the code you wrote and the original Json, my objectArray would have two Month objects ("2010-12" and "2011-01") then the Month object would contain an array which would have two items, one for each category, which would need to contain an object which contains the "category name", "rate", "level" and "total" values.

Any help you could offer would be great.

Thanks,

Scrooby

[smasher]

The initWithDate:dictionary: needs to do the same thing - loop through the keys, get the object, and pass it to the category init method.

//in your Month.h
NSMutableArray *categoryArray

//in your Month.m
- (id) initWithDate:(NSString*)date dictionary:(NSDictionary*)categoryDict
{
	self = [super init];
	if (self != nil) {

		categoryArray = [[NSMutableArray alloc] init];		 
	
		for (NSDictionary *catKey in categoryDict){
			//catKey is "category1"
			NSDictionary *attributes = [categoryDict objectForKey:catKey];
			Category *cat = [[Category alloc] initWithKey:catKey dictionary:attributes];
			[categoryArray addObject:cat];
			[cat release];
		}

	}
	return self;
}

EXTRA CREDIT: If you had a choice then this would be easier with arrays in the JSON. The structure would be easier to parse if all data is in values, not the keys, and your object structure could exatly mirror the JSON structure. There would be less mind-bending data juggling that way.

{
    "data": [
        {
            "month": "2010-12",
            "categories": [
                {
                    "category": "category1",
                    "rate": "xx",
                    "level": "xx",
                    "total": "xx" 
                },
                {
                    "category": "category2",
                    "rate": "xx",
                    "level": "xx",
                    "total": "xx" 
                } 
            ] 
        },
        {
            "month": "2011-01",
            "categories": [
                {
                    "category": "category1",
                    "rate": "xx",
                    "level": "xx",
                    "total": "xx" 
                },
                {
                    "category": "category2",
                    "rate": "xx",
                    "level": "xx",
                    "total": "xx" 
                } 
            ] 
        } 
    ]
}

[Scrooby]

That's fantastic, it works great!

Thanks for all your help!