Question

I am receining NSData in following way

 - (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
    { 
    char *ptr = (void *)[data bytes]; // set a pointer to the beginning of your data   bytes

I am receiving the data then I need to compare this data with following array

        char ch[3]={0x04,0x01,0X00};

becuase that data is coming from server, but data is dynamic i need to compare many such arrays with server data i found following method but it is static method but can no compare all arrays in following way

     if(*ptr == 0x04) {
       }
      ptr++;
      if(*ptr == 0x01) {
       }
  ptr++;
  if(*ptr==0X00){
       }
but i can not compare all array so please help how 

i can compare

              char *ptr = (void *)[data bytes];

with

               char ch[3]={0x04,0x01,0X00};

please help

Answer 1

If you use an NSData object for the data you are comparing (ch[3]), then you can use -[NSData rangeOfData:options:range:] to find the pattern.

Here is an example

//This is just mock up data to represent what would be passed into your method
unsigned char ch1[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x04, 0x01, 0x00, 0x0F }; 
NSData *data1 = [[NSData alloc] initWithBytes:ch1 
                                       length:sizeof(ch1)];
//This is the data used for the comparison
NSData *data2 = [[NSData alloc] initWithBytes:(unsigned char[]){0x04, 0x01, 0x00} 
                                       length:3];

NSRange range = [data1 rangeOfData:data2 
                           options:0 
                             range:NSMakeRange(0, [data1 length])];

if(range.location != NSNotFound)
{
     NSLog(@"Found pattern!");
}