CODEWITHSUNDEEP
iosjson
user1003426
user1003426

Reputation: 25

iOS : JSON String to NSArray not working as expected

How to parse a a JSON string in iOS app? Using SBJSON. Running the code below. Getting data is successful but the count on the number of entries in the array is zero even tho the JSON string contains entries. My question is how query the JSON string in a loop?

Thanks!

// Create new SBJSON parser object
SBJsonParser *parser = [[SBJsonParser alloc] init];

// Prepare URL request to download statuses from Twitter
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://safe2pee.org/api/proxlist.php?location=37.7626214,-122.4351661&distance=1"]];

// Perform request and get JSON back as a NSData object
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];

// Get JSON as a NSString from NSData response
NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];

NSLog(@"string equal = %@", json_string);

// parse the JSON response into an object
// Here we're using NSArray since we're parsing an array of JSON b objects
NSArray *bathrooms = [parser objectWithString:json_string error:nil];

NSLog(@"count = %d", [bathrooms count]);

// Each element in bathrooms is a single bathroom
// represented as a NSDictionary
for (NSDictionary *bathroom in bathrooms)
{
    // You can retrieve individual values using objectForKey on the bathroom NSDictionary
    // This will print the tweet and username to the console
    NSLog(@"%@ - %@", [bathroom objectForKey:@"name"], [[bathroom objectForKey:@"lat"] objectForKey:@"long"]);
}

Upvotes: 0

Views: 1933

Answers (2)

Tim Dean
Tim Dean

Reputation: 8292

I looked at the JSON string returned when I request the URL in your post, and it looks like it is being improperly truncated by the server. The JSON string returned contains a dictionary structure containing, among other things, a key called "bathrooms" whose value is an array of dictionary structures. Each of those bathroom dictionary structures contains several fields including "bid", "name", "lat", ..., "directions", and "comment".

When I scroll to the end of the JSON I received, I see a complete dictionary structure under the "bathrooms" array ("bid" is "MTIyIFMyUA==", "name" is "Momi Tobi's". That dictionary structure contains its closing brace but the closing "]" for the array is missing and the closing "}" for the top-level dictionary structure is missing.

You should look to the service to see why it is returning invalid JSON strings. Once you have a valid string it looks like you should be starting with an NSDictionary and parsing it something like this:

NSDictionary *result = [parser objectWithString:json_string error:nil];
NSArray *bathrooms = [result objectForKey:@"bathrooms"];

Upvotes: 0

Lily Ballard
Lily Ballard

Reputation: 185671

It's because it's not working. That's not a valid JSON string. That's 2 JSON dictionaries, back to back, with a comma in between. It's missing the wrapping []. If you actually test the result value of -objectWithString:error:, you'd see it's nil, and if you pass in an NSError** to the error parameter there, you'd get back an error message telling you it's invalid JSON.

Upvotes: 2

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