Parsing a config file

Question

I have a config file whose content is something like this:

main = {
delay = 10000;  
inputs = (
    {
        enabled = true;
        ip = "127.0.0.1"; 
        port = 10001; 
        file = "c:\abc.txt";
    },
    {
        enabled = true;
        ip = "127.0.0.1"; 
        port = 10002; 
        file = "c:\myfile.txt";
    },
);
}

Now, I want to parse this file, and for example, get the port number of the second input (i.e., 10002 in this example), etc.

Do you know what is the easiest way to do so in objective C?

Thanks!

That looks like the NSLog output (or `description`) of a `NSDictionary`, which is not suitable as config file format because it cannot reliably be parsed back (compare http://stackoverflow.com/questions/16783635/nsarray-to-description-and-vice-versa for a similar issue). - If possible, choose a different config file format (e.g. JSON). — Martin R, Dec 20 '13 at 17:59

score 1 · Answer 1 · answered Dec 20 '13 at 17:20

Make sure it's a valid JSON file and then create a NSJSONSerialization object from the NSData of the file after opening it.

NSJSONSerialization *config = [[NSJSONSerialization JSONObjectWithData:DATAFROMFILE options:NSJSONReadingMutableContainers error:nil];

Then to access the second input port:

config[@"inputs"][1][@"port"]

But the best way to do this would be to create a model from each input so you could access the properties as strongly typed properties instead of by key.

ie. config.port instead of configInput[@"port"]

score 0 · Answer 2 · edited May 23 '17 at 11:56

0

If you are able to change or modify the configuration file format to json or plist, you could simply use built in readers an parsers.

Else, there are third party approaches like libconfig.

Also this question may help.

edited May 23 '17 at 11:56

Community

1
1

answered Dec 20 '13 at 17:19

denolk

765
14
27

Yas Tabasam · Accepted Answer · 2013-12-22T00:05:20.393

Looks like your config contents were output by NSLog, which results in invalid JSON hence assuming that your actual config file is a valid JSON object, following code should get you what you need:

//Don't forget to replace "configfile" with your config file name in the project
NSString *configPath = [[NSBundle mainBundle] pathForResource:@"configfile" ofType:nil];
NSData *data = [[NSFileManager defaultManager] contentsAtPath:configPath];
NSDictionary *config = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:nil];
NSArray *ports = [config valueForKeyPath:@"main.inputs.port"];

//ports[0] is 10001
//ports[1] is 10002

Here you can verify if your JSON is valid: http://jsonlint.com. This is how your valid JSON confi should look like:

{
    "main": {
        "delay": "10000",
        "inputs": [
            {
                "enabled": true,
                "ip": "127.0.0.1",
                "port": 10001,
                "file": "c: \\abc.txt"
            },
            {
                "enabled": true,
                "ip": "127.0.0.1",
                "port": 10002,
                "file": "c: \\myfile.txt"
            }
        ]
    }
}

EDIT:

I would personally use a model framework rather than just a json parser to save you from a ton of manual work that comes with built-in NSJSONSerialization class. Here are couple of pretty good ones:

1) GitHub Mantle - https://github.com/MantleFramework/Mantle I use it where ever I can. It is very well written and thought out framework but has a little bit of learning curve involved, which probably is true to any new piece of software.

2) SBJson - https://github.com/stig/json-framework You can use SBJson if you just wanna get the job done, it has been pretty popular, especially before Mantle and other frameworks became available.

I hope it helps.

thanks, but do you know any free and simple JSON parser for objective C? — Blue Sky, Dec 21 '13 at 09:21
@BlueSky: `NSJSONSerialization` is "built-in" as part of the Foundation frameworks. — Martin R, Dec 21 '13 at 09:27
@MartinR : thanks, I use gcc. Which header file should I use so that I can use NSJSONSerialization? — Blue Sky, Dec 21 '13 at 09:33
@BlueSky: Do you use Xcode? Just `@import ` (which is usually already done in the precompiled header). — Martin R, Dec 21 '13 at 09:37
@MartinR No, I use MingW (gcc under Windows). Now, what file should I include? — Blue Sky, Dec 21 '13 at 09:42
@BlueSky: Sorry, I have no experience with MingW. - But perhaps you should add that information to your question (and tag the question with [mingw]). — Martin R, Dec 21 '13 at 09:44
@BlueSky - I've edited my question added a couple of JSON parsers/frameworks. Please take a look. — Yas Tabasam, Dec 22 '13 at 00:07

Parsing a config file

3 Answers3