How do I deserialize a JSON string into an NSDictionary? (For iOS 5+)

Question

In my iOS 5 app, I have an NSString that contains a JSON string. I would like to deserialize that JSON string representation into a native NSDictionary object.

 "{\"password\" : \"1234\",  \"user\" : \"andreas\"}"

I tried the following approach:

NSDictionary *json = [NSJSONSerialization JSONObjectWithData:@"{\"2\":\"3\"}"
                                options:NSJSONReadingMutableContainers
                                  error:&e];  

But it throws the a runtime error. What am I doing wrong?

-[__NSCFConstantString bytes]: unrecognized selector sent to instance 0x1372c 
*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '-[__NSCFConstantString bytes]: unrecognized selector sent to instance 0x1372c'

Answer 1

It looks like you are passing an NSString parameter where you should be passing an NSData parameter:

NSError *jsonError;
NSData *objectData = [@"{\"2\":\"3\"}" dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:objectData
                                      options:NSJSONReadingMutableContainers 
                                        error:&jsonError];