CODEWITHSUNDEEP
iosobjective-cjson
Daniel Watson
Daniel Watson

Reputation: 225

Previous NSDictionary now to JSON array

- (void)retrieveData
{
    NSURL * url = [NSURL URLWithString:@"***/connection.php"];
    NSData * data = [NSData dataWithContentsOfURL:url];

    _json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];

    _questionsArray = [[NSMutableArray alloc]init];

    for (int i = 0; i < _json.count; i++)
    {
        NSString * qID = [[_json objectAtIndex:i] objectForKey:@"id"];
        NSString * qTitle = [[_json objectAtIndex:i] objectForKey:@"question_title"];
        NSString * qA = [[_json objectAtIndex:i] objectForKey:@"A"];
        NSString * qB = [[_json objectAtIndex:i] objectForKey:@"B"];
        NSString * qC = [[_json objectAtIndex:i] objectForKey:@"C"];
        NSString * qD = [[_json objectAtIndex:i] objectForKey:@"D"];
        NSString * qAnswer = [[_json objectAtIndex:i] objectForKey:@"question_answer"];

        question * myQuestion = [[question alloc] initWithQuestionID:qID andQuestionName:qTitle andQuestionA:qA andQuestionB:qB andQuestionC:qC andQuestionD:qD andQuestionAnswer:qAnswer];

        [_questionsArray addObject:myQuestion];
    }

    [_json enumerateObjectsUsingBlock:^(NSDictionary *questionDictionary, NSUInteger idx, BOOL *stop) {
        //Here I'm treating the index like an NSNumber, if your code is expecting a string instead use
        //@(idx).stringValue
        [_questions setObject:questionDictionary forKey:@(idx)];

        //or the modern equivalent
        //questions[@(idx)] = questionDictionary;

        //If you want to use your 'questions class' then create one and put it into the array instead of the dictionary pulled from the array.
    }];

    NSLog( @"%@", _questions );

}

Logs (null)

random gobledy gook so my post isn't mostly code random gobledy gook so my post isn't mostly code random gobledy gook so my post isn't mostly code random gobledy gook so my post isn't mostly code random gobledy gook so my post isn't mostly code

Upvotes: 1

Views: 70

Answers (1)

Brandon
Brandon

Reputation: 2427

If I understand your question correctly it becomes something like this

self.questions = .... //I assume this is the array you reference 'question' objects that is created by your retrieve data method

//this used to be created by pulling an object out of your questions dictionary with the key i interpreted as a string.
//now that it's an array you should be able to just reference it by index, assuming they were inserted in order
//I'm also assuming that what comes out of the aray is a question object given the code you provided with the signature
//- (id) initWithQuestionID: (NSString *) qID andQuestionName: (NSString *) qName andQuestionA: (NSString *) qA andQuestionB: (NSString *) qB andQuestionC: (NSString *) qC andQuestionD: (NSString *) qD andQuestionAnswer: (NSString *) qAnswer
Question *nextQuestion = self.questions[i];


self.answer = nextQuestion.questionAnswer;
self.questionLabel.text = nextQuestion.questionLabel;
//and so on

I also suggest the following edit to replace your for loop. It uses a for in loop instead, this saves you from having to keep track of an index and looks cleaner. It also helps so you don't keep repeating the [_json objectAtIndex:i] chunk of code. I also use modern objective-c syntax to access the dictionary.

for (NSDictionary *questionDictionary in _json)
{
    NSString * qID = questionDictionary[@"id"];
    NSString * qTitle = questionDictionary[@"question_title"];

    ...
    question * myQuestion = [[question alloc] initWithQuestionID:qID andQuestionName:qTitle andQuestionA:qA andQuestionB:qB andQuestionC:qC andQuestionD:qD andQuestionAnswer:qAnswer];
    [_questionsArray addObject:myQuestion];
}

If you need the key along with the object in the dictionary then you can clean it up in a similar way with the enumerateObjectsUsingBlock 

[_json enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
    //your code here
}];

EDIT

It sounds like what your really wanting to do is to pull down your JSON but keep all your other code the way it was when you were using a dictionary that you got from your plist. So in this case you want your parsing function to return a dictionary instead of an array. If that's the case it's worth sidestepping into computer science for a second.

NSDictionarys are also known as a hash, map, symbol table, or associative array. Some languages (such as Lua) don't have an array collection like NSArray, they only have dictionaries. From a dictionary you can create many of the other collections your used to like arrays (and sets too). Heres how it works: Instead of an ordered collection of elements with an index, you place the items in a dictionary and use what would have been the index as the key, and the value becomes, well, the value. For example an array and it's equivalent associative array (aka dictionary):

NSArray *array = @[@"hello", @"world", @"!"];

NSDictionary *dictionary = @{@(1): @"hello",
                             @(2): @"world",
                             @(3): @"!"};

This is exactly what your doing when you load in the data from your plist because the first elements key is 0 followed by another dictionary, and I'm supposing that the next element in the list is 1 followed by another dictionary. Inside your parsing function it becomes 

NSMutableDictionary *questions = [[NSMutableDictionary alloc] init];
[_json enumerateObjectsUsingBlock:^(NSDictionary *questionDictionary, NSUInteger idx, BOOL *stop) {
    //Here I'm treating the index like an NSNumber, if your code is expecting a string instead use
    //@(idx).stringValue
    [questions setObject:questionDictionary forKey:@(idx)];

    //or the modern equivalent
    //questions[@(idx)] = questionDictionary;

    //If you want to use your 'questions class' then create one and put it into the array instead of the dictionary pulled from the array.
}];

This of course assumes that your api is going to return the JSON questions in the order you want.

Upvotes: 2

Related Questions