Question

I am trying to do a string comparison in iOS with a string obtained from a network stream.

The code that reads the stream is:

uint8_t buffer[1024];
int len;
    while ([inputStream hasBytesAvailable]) 
    {
        len = [inputStream read:buffer maxLength:sizeof(buffer)];
        if (len > 0) 
        {
            NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];
            [self handleServerResponse: intCommand Response:output];
         }else{
            [self endComms];
         }
     }

The server at the other end always produces responses of 1024 bytes, with chr(0) being placed at the end of the data to fill the buffer.

When I do a string comparison:

if (strCut==@"B") {
   //do something...
}

I always get a negative result, presumably because the string contaings the response and lots of null characters.

I would like to be able to strip empty characters from the buffer when reading the response into the string, but I not having any luck in doing this in iOS.

Help appreciated!

Thanks.

Dave

Answer 1

You’re making a bad assumption about why your code is not working.

Change:

if (strCut == @"B")

to:

if ([strCut isEqualToString:@"B"])

For future reference never make assumptions – use a debugger or other tools to verify what the problem is. You might also want to consider reading an introductory book on Objective-C.