Question

I’ve looked into this a lot on stack overflow and have found some instances where it may work for what I want to do, but I’m not gonna lie, I’m a tad lost. I have a very simple string that shows up on a webpage that i want to read into the application, parse it, then display it inside some UITextFields. The URL is mtgox.com/data/code/ticker.php. It’s a php page that yields a simple JSON string, a one liner, looking like the following:

{"ticker":{"high":14.6999,"low":14.04,"avg":14.379509781,"vol":10981,"last":14.44278,"buy":14.4302,"sell":14.44278}}

How can I read this string into my application and then parse it? I was thinking of possibly using the UIWebView class and the stringByEvaluatingJavaScriptString method on the site, but I don’t know much about javascript, nor do I know if that would work.

I’ve seen some people mentioning the use of a JSON library, but don’t know if that’s what will be the best for what I need, and if that will even work; and I feel that might be a tad overkill given I’m only parsing one line.

Answer 1

If you insist not to use JSON parser (library installation and other framework config hasle), the
code below has been tested and work fine for your URL:

Place this code in the view controller that has the textfield.

- (NSDictionary *)parseJSONFromSomeURL
{
    NSURL *pageURL = [NSURL URLWithString:@"http://mtgox.com/code/data/ticker.php"];
    NSString *JSONString = [NSString stringWithContentsOfURL:pageURL encoding:NSUTF8StringEncoding error:nil];

    JSONString = [JSONString stringByReplacingOccurrencesOfString:@"{" withString:@""];
    JSONString = [JSONString stringByReplacingOccurrencesOfString:@"}" withString:@""];
    JSONString = [JSONString stringByReplacingOccurrencesOfString:@"\"" withString:@""];

    NSArray *components = [JSONString componentsSeparatedByString:@","];

    NSMutableDictionary *result = [NSMutableDictionary dictionary];
    for (NSString *parts in components)
    {
        NSArray *subComponents = [parts componentsSeparatedByString:@":"];
        // First element has 3 items (it has ticker)
        if ([subComponents count] > 2)
        {
            [result setValue:@"" forKey:[subComponents objectAtIndex:0]];
            [result setValue:[subComponents objectAtIndex:2] forKey:[subComponents objectAtIndex:1]];
        }
        else
        {
            [result setValue:[subComponents objectAtIndex:1] forKey:[subComponents objectAtIndex:0]];
        }
    }

    return result;
}

Hopefully it help to solve your problem.