Interesting stuff i came to know about which i was unaware of. This post is more of a discussion on the problem. I haven’t understood the solution and so would request you to have a say.

I have done json parsing numerous times. I can tell if json is valid or not by looking it. I was using google-gson for android application and its awesome. Application was supported by php web service. The solution that fixed the problem is related to php and i am not a php developer and don’t have that much inner understanding of it. It was regular json parsing routine. Application just crashed when gson was parsing the json response from php service.

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 2

From error I understood the reason but that was not it. I was very confident that something else was the problem because json response was perfect. I wrote quick objective-c routine(SBJSON) to parse same json response and it worked there. I even did validation on jsonlint.com
After doing bit of research I came across a working solution. In php before sending response I had to put this:

ob_clean();
echo header('Content-Type: application/json');

I checked the php manual to understand what those lines means, header function was quite obvious. According to manual, ob_clean:

This function discards the contents of the output buffer.

Now I have no idea why discarding the contents of output buffer was working. This was the case for android, I mean in iphone I didn’t need ob_clean. I am still looking for the explanation on this.