Parse JSON contents in local file

Question

How can I parse my JSON file stored in the application?

These are in my JSON file contents:

[{"number":"01001","lieu":"paris"}{"number":"01002","lieu":"Dresden"}]

I’ve tried the following code:

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"file" ofType:@"json"];

//création d'un string avec le contenu du JSON
NSString *myJSON = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:NULL];   

//Parsage du JSON à l'aide du framework importé
NSDictionary *json    = [myJSON JSONValue];

NSArray *statuses    =  [json objectForKey:@"number"];

for (NSDictionary *status in statuses)
{
    NSLog(@"%@ ", [status objectForKey:@"lieu"]);
}

score 25 · Answer 1 · edited Mar 14 '16 at 11:44

Firstly, note there’s a comma missing between the two objects in your JSON string.

Secondly, note that your JSON string contains a top-level array. So, instead of:

NSDictionary *json = [myJSON JSONValue];

use:

NSArray *statuses = [myJSON JSONValue];

Each element in the array is an object (a dictionary) with two name-value pairs (key-object pairs), one for number and another one for lieu:

for (NSDictionary *status in statuses) {
    NSString *number = [status objectForKey:@"number"];
    NSString *lieu = [status objectForKey:@"lieu"];

    …
}

You might also want to check whether the file could be read:

//Creating a string with the contents of JSON
NSString *myJSON = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:NULL];
if (!myJSON) {
    NSLog(@"File couldn't be read!");
    return;
}

score 2 · Answer 2 · answered May 26 '16 at 17:18

Here is a suggested full implementation:

NSString *jsonFilePath = [[NSBundle mainBundle] pathForResource:@"file" ofType:@"json"];
if (!jsonFilePath) {
    // ... do something ...
}

NSError *error = nil;
NSInputStream *inputStream = [[NSInputStream alloc] initWithFileAtPath:jsonFilePath];
[inputStream open];
id jsonObject = [NSJSONSerialization JSONObjectWithStream: inputStream
                                                        options:kNilOptions
                                                          error:&error];
[inputStream close];
if (error) {
    // ... do something ...
}

Parse JSON contents in local file

2 Answers2