importing data from a json file

Question

I created some json data and saved it in a file named quizdata.json in xcode. I then selected the project target and clicked on Editor/ Add Build Phase/ Add Copy File Build Phase, selected the Products Directory and dropped the quizdata.json file in the space provided. I did not indicate a subpath because I read it wasn't needed and I don't know it :(

I then added the four lines at the bottom of this main function to import the file and serialize it into an object. However, when I run the code it's showing null when the json data should be output

Imported Questions: (null)
Program ended with exit code: 0

Can you explain why it's null?

main int main(int argc, const char * argv[]) {

    @autoreleasepool {
        // Create the managed object context
        NSManagedObjectContext *context = managedObjectContext();

        // Custom code here...
        // Save the managed object context
        NSError *error = nil;
        if (![context save:&error]) {
            NSLog(@"Error while saving %@", ([error localizedDescription] != nil) ? [error localizedDescription] : @"Unknown Error");
            exit(1);
        }

        NSError* err = nil;
        NSString* dataPath = [[NSBundle mainBundle] pathForResource:@"quizdata" ofType:@"json"];
        NSArray* Questions = [NSJSONSerialization JSONObjectWithData:[NSData dataWithContentsOfFile:dataPath]
                                                         options:kNilOptions
                                                           error:&err];
        NSLog(@"Imported Questions: %@", Questions);
    }
    return 0;
}

Sample from quizdata.json

[{ "question" : "Do you like hairy fruit ?????????????????????????????", "answer1": "yes", "answer2": "no because my mouhth is like a large elastic band on tuesdays", "answer3": "maybe wonder never tried it but i should naturally", "answer4":"of course i do you beast of a man with a hairy nose", "correctAnswer": "yes", "unique": "1", "name": "fruitquiz", "quizId: 1"}
{ "question" : "Do you like fruit", "answer1": "yes", "answer2": "no", "answer3": "maybe", "answer4":"of course", "correctAnswer": "yes", "unique": "2", "name": "fruitquiz", "quizId: 1"}
...

@Lukasz'Severiaan'Grela I'm not sure if I understand your comment, but err is set to nil in the code that I copied from this blog tutorial for importing data raywenderlich.com/12170/… — BrainLikeADullPencil
yes you set it to nil initialy and call to NSJSOMSerialization JSONObjectWithData... will set it to NSError if there is an error so put this before you NSLog: if(err) NSLog("Error %@",[err description]); — Lukasz 'Severiaan' Grela
@Lukasz'Severiaan'Grela ok, thanks for that. There's a problem with the json data.... "The data couldn’t be read because it has been corrupted." (No value for key in object around character 375.) UserInfo=0x100515060 {NSDebugDescription=No value for key in object around character 375.} — BrainLikeADullPencil
1) Check that "dataPath" is valid. 2) Break the "dataWithContentsOfFile" out on a separate line, assign to a temp, and make sure that's valid. (The first thing to do in a situation like this is verify all your inputs so that you know precisely which step is failing.) — Hot Licks

Nirav Jain Nirav Jain · Accepted Answer · 2014-04-17T14:06:10

1) Make Sure file is available in resource.

2) Check NSData length. (if data length is zero then it can be your json file issue, make sure you are validating json file)

3) Save data as per your need in NSArray or NSDictionary.

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"example" ofType:@"json"];
NSData *data = [NSData dataWithContentsOfFile:filePath];
NSArray *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];

(Note : You can check your file on http://www.jsoneditoronline.org/ (for reference only))

importing data from a json file

1 Answers