create a json string from NSArray

Question

In my iPhone aplication I have a list of custom objects. I need to create a json string from them. How I can implement this with SBJSON or iPhone sdk?

 NSArray* eventsForUpload = [app.dataService.coreDataHelper fetchInstancesOf:@"Event" where:@"isForUpload" is:[NSNumber numberWithBool:YES]];
    SBJsonWriter *writer = [[SBJsonWriter alloc] init];  
    NSString *actionLinksStr = [writer stringWithObject:eventsForUpload];

and i get empty result.

See this question similar to yours : http://stackoverflow.com/questions/9139454/objective-c-ios-converting-an-array-of-objects-to-json-string — Armaan Stranger, Jul 23 '13 at 12:23
@revolutionkpi I know it's an old question, but it might help others if you accepted one of the answers as a solution to mark the question as solved — Rimon, Aug 20 '19 at 08:43

Thilina Chamath Hewagama · Answer 1 · 2015-02-05T17:42:42.970

61

This process is really simple now, you don't have to use external libraries, Do it this way, (iOS 5 & above)

NSArray *myArray;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:myArray options:NSJSONWritingPrettyPrinted error:&error];
NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

edited Feb 05 '15 at 17:42

answered Nov 27 '13 at 06:17

Thilina Chamath Hewagama

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Damo · Answer 2 · 2014-10-22T08:10:43.673

11

I love my categories so I do this kind of thing as follows

@implementation NSArray (Extensions)

- (NSString*)json
{
    NSString* json = nil;

    NSError* error = nil;
    NSData *data = [NSJSONSerialization dataWithJSONObject:self options:NSJSONWritingPrettyPrinted error:&error];
    json = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

    return (error ? nil : json);
}

@end

edited Oct 22 '14 at 08:10

answered Mar 20 '14 at 22:41

Damo

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1

Better with a little simple error control: return (error ? nil : json); – anavarroma Oct 21 '14 at 16:19

score 6 · Answer 3 · answered Aug 11 '15 at 11:56

Although the highest voted answer is valid for an array of dictionaries or other serializable objects, it's not valid for custom objects.

Here is the thing, you'll need to loop through your array and get the dictionary representation of each object and add it to a new array to be serialized.

 NSString *offersJSONString = @"";
 if(offers)
 {
     NSMutableArray *offersJSONArray = [NSMutableArray array];
     for (Offer *offer in offers)
     {
         [offersJSONArray addObject:[offer dictionaryRepresentation]];
     }

     NSData *offersJSONData = [NSJSONSerialization dataWithJSONObject:offersJSONArray options:NSJSONWritingPrettyPrinted error:&error];

     offersJSONString = [[NSString alloc] initWithData:offersJSONData encoding:NSUTF8StringEncoding] ;
 }

As for the dictionaryRepresentation method in the Offer class:

- (NSDictionary *)dictionaryRepresentation
{
    NSMutableDictionary *mutableDict = [NSMutableDictionary dictionary];
    [mutableDict setValue:self.title forKey:@"title"];

    return [NSDictionary dictionaryWithDictionary:mutableDict];
}

score 2 · Answer 4 · edited Feb 04 '17 at 10:37

2

Try like this Swift 2.3

let consArray = [1,2,3,4,5,6]
var jsonString : String = ""
do
{
    if let postData : NSData = try NSJSONSerialization.dataWithJSONObject(consArray, options: NSJSONWritingOptions.PrettyPrinted)
    {
        jsonString = NSString(data: postData, encoding: NSUTF8StringEncoding)! as String
    }
}
catch
{
    print(error)
}

edited Feb 04 '17 at 10:37

Tunaki

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answered Feb 04 '17 at 10:26

Mohammad Kamran Usmani

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score 0 · Answer 5 · answered Jul 23 '13 at 12:41

0

Try like this,

- (NSString *)JSONRepresentation {
    SBJsonWriter *jsonWriter = [SBJsonWriter new];    
    NSString *json = [jsonWriter stringWithObject:self];
    if (!json)

    [jsonWriter release];
    return json;
}

then call this like,

NSString *jsonString = [array JSONRepresentation];

Hope it will helps you...

answered Jul 23 '13 at 12:41

Venk

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I suspect that the problem is the "custom objects", which the writer must somehow know how to interpret. Much easier if everything is in arrays/dictionaries. – Hot Licks Jul 23 '13 at 12:46
2

The above code is broken. Either it will fail to compile under ARC, because you call release, or it will leak memory because you only release the writer if you fail to JSONify `self`. – Stig Brautaset Aug 08 '13 at 21:11

score 0 · Answer 6 · edited Sep 09 '16 at 08:51

0

I'm a bit late to this party, but you can serialise an array of custom objects by implementing the -proxyForJson method in your custom objects. (Or in a category on your custom objects.)

For an example.

edited Sep 09 '16 at 08:51

Jagat Dave

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answered Oct 26 '14 at 20:23

Stig Brautaset

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create a json string from NSArray

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