converting NSMutableData to NSMutableDictionary?

i am accumulating data from NSMutableDictionary to NSMutabledata like

    NSMutableData *da开发者_Python百科ta = [receivedData objectForKey:@"tag1"];

and also

    data  = [receivedData objectForKey:@"tag2"];

after this one , how can i get data for @"tag2" only from NSMutableData?

 NSMutableData tag2Data = [Data forKey:@"tag2"]; 

is not working?

I'm unsure exactly what you are trying to do here, but it doesn't look like you are using the proper class. If you check the class reference from Apple there is a link to a great code example of getting a string out of an NSMutableData object, but the only way to access the data inside it is using getBytes.