Send Data packet to Client

Question

I need to sent NSData which holds JSON Strings as well total number of length in form of (length of actual string+actual string).I need to send a packet of data that reserves first 10 bytes for length of string and followed by string

while sending NSData object I also need to send its length in first 10 bytes followed by data like :

length of data + JSON string = total data sent to java client .

further java client will read first 10 byte to know actual length of data coming to make an byte array and move further.

Answer 1

This brute force example uses first 10 characters for string representation of payload length followed by actual payload.

NSArray *arrPayload = @[@"Hello", @"world"];

NSData *jsonData = [NSJSONSerialization dataWithJSONObject:arrPayload
                                                   options:0
                                                     error:nil];

NSString *jsonString = [[NSString alloc] initWithData:jsonData
                                             encoding:NSUTF8StringEncoding];

NSString *comboString = [NSString stringWithFormat:@"%010lu%@", 
                            (unsigned long)jsonString.length, jsonString];

NSLog(@"%@", comboString);

NSData* combinedData = [comboString dataUsingEncoding:NSUTF8StringEncoding];

result:

0000000017["Hello","world"]

But: if this is supposed to be sent as a HTTP request you might want to consider using Content-Length header to pass the length information instead.