how can i replace json string?

Question

i want to replace particular data's in json string

Answer 1

Parse it, make the changes you need, then serialize it back out. You didn't say what JSON library you're using, but it should be fairly easy.

Answer 2

Without knowing the specifics of your problem:

[jsonString stringByReplacingOccurrencesOfString:@"replaceme" withString:@"replacement"];

But you're probably far better of using a JSON library.