Cocoa-Touch - How parse local Json file

Question

I\'m newbie in iOS dev and I\'m trying to parse a local Json file such as

{\"quizz\":[{\"id\":\"1\",\"Q1\":\"When Mickey was born\",\"R1\":\"1920\",\"R2\":\"1

Answer 1

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"fileName" ofType:@"json"];
NSString *myJSON = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:NULL];
NSError *error =  nil;
NSArray *jsonDataArray = [NSJSONSerialization JSONObjectWithData:[myJSON dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&error];

Answer 2

Swift 2.3 I use a utility method to convert JSON files to a Dictionary:

func getDictionaryFromJSON(jsonFileName: String) -> [String: AnyObject]? {
    guard let filepath = NSBundle.mainBundle().pathForResource(jsonFileName, ofType: "json") else {
        return nil
    }

    guard let data = NSData(contentsOfFile: filepath) else {
        return nil
    }

    do {
        let dict = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String: AnyObject]
        return dict
    } catch {
        print(error)
        return nil
    }
}

Answer 3

JSON has a strict key/Value notation, your key/value pairs for R4 and response are not correct. Try this:

NSString *jsonString = @"{\"quizz\":[{\"id\":\"1\",\"Q1\":\"When Mickey was born\",\"R1\":\"1920\",\"R2\":\"1965\",\"R3\":\"1923\",\"R4\":\"1234\",\"response\":\"1920\"}]}";

^{If you read the string from a file, you don't need all the slashes}
Your file would be something like this:

{"quizz":[{"id":"1","Q1":"When Mickey was born","R1":"1920","R2":"1965","R3":"1923","R4":"1234","response":"1920"},{"id":"1","Q1":"When start the cold war","R1":"1920","R2":"1965","R3":"1923","R4":"1234","reponse":"1920"}]}

---

I tested with this code:

NSString *jsonString = @"{\"quizz\":[{\"id\":\"1\",\"Q1\":\"When Mickey was born\",\"R1\":\"1920\",\"R2\":\"1965\",\"R3\":\"1923\",\"R4\":\"1234\",\"response\":\"1920\"}, {\"id\":\"1\",\"Q1\":\"When start the cold war\",\"R1\":\"1920\",\"R2\":\"1965\",\"R3\":\"1923\",\"R4\":\"1234\",\"reponse\":\"1920\"}]}";
NSLog(@"%@", jsonString);
NSError *error =  nil;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:[jsonString dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&error];

NSArray *items = [json valueForKeyPath:@"quizz"];

NSEnumerator *enumerator = [items objectEnumerator];
NSDictionary* item;
while (item = (NSDictionary*)[enumerator nextObject]) {
    NSLog(@"clientId = %@",  [item objectForKey:@"id"]);
    NSLog(@"clientName = %@",[item objectForKey:@"Q1"]);
    NSLog(@"job = %@",       [item objectForKey:@"Q2"]);
}

I got the impression, that you copied old code, as you are not using apple's serialization and a Enumerator instead of Fast Enumeration. The whole enumeration stuff could be written simple as

NSArray *items = [json valueForKeyPath:@"quizz"];
for (NSDictionary *item in items) {
    NSLog(@"clientId = %@",  [item objectForKey:@"id"]);
    NSLog(@"clientName = %@",[item objectForKey:@"Q1"]);
    NSLog(@"job = %@",       [item objectForKey:@"Q2"]);
}

or even fancier with block based enumeration, hwere you have additionaly an index if needed to the fast and secure enumeration.

NSArray *items = [json valueForKeyPath:@"quizz"];
[items enumerateObjectsUsingBlock:^(NSDictionary *item , NSUInteger idx, BOOL *stop) {
    NSLog(@"clientId = %@",  [item objectForKey:@"id"]);
    NSLog(@"clientName = %@",[item objectForKey:@"Q1"]);
    NSLog(@"job = %@",       [item objectForKey:@"Q2"]);
}];

Answer 4

There seems to be a typo in your json file.

Replace
"R4","1234","response","1920" with "R4":"1234","response":"1920"
and
"rep4","1234","reponse","1920" with "rep4":"1234","response":"1920"

Answer 5

Use jsonlint.com to find errors in your JSON string.
In this case, it says you have non-valid JSON near "R4"