How to get specified data from stream? - ios

Question

I did simple app that connects to tcp stream server(OBD wifi connection in car).
It connects and works pretty well - I can send messages and get answers from car. Now I want to read only specified data from answer. When I send request to car for example 01041 it will answer something like this:
SEARCHING: OK
41 04 7F
I want create a variable that will contain only last bytes of this answer. In this example it will be 7F. I want do this because I'd like to present that data in Label. So I need to skip in this example line Searching and skip first 2 bytes in line 2 to get only 7F. How I can do it?
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)initNetworkCommunication {
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)#"192.168.0.10", 35000, &readStream, &writeStream);
self.inputStream = objc_unretainedObject(readStream);
self.outputStream = objc_unretainedObject(writeStream);
[self.inputStream setDelegate:self];
[self.outputStream setDelegate:self];
[self.inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[self.outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[self.inputStream open];
[self.outputStream open];
}
- (IBAction)Connect:(id)sender {
[self initNetworkCommunication];
}
- (IBAction)Play:(id)sender {
NSString *response = [NSString stringWithFormat:#"01041\r\n"];
[NSThread sleepForTimeInterval:0.05];
NSData *data = [[NSData alloc] initWithData:[response dataUsingEncoding:NSUTF8StringEncoding]];
}
-(void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
{
switch (eventCode) {
case NSStreamEventOpenCompleted:
[self.logTextView setText:[self.logTextView.text stringByAppendingString:#"Stream opened\n"]];
break;
case NSStreamEventHasBytesAvailable:
if (aStream == self.inputStream) {
uint8_t buffer[1024];
long len;
while ([self.inputStream hasBytesAvailable]) {
len = [self.inputStream read:buffer maxLength:sizeof(buffer)];
if (len > 0) {
NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];
//NSString *oborty = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];
if (nil != output) {
[self.logTextView setText:[self.logTextView.text stringByAppendingString:output]];
[self.RPM setText:[self.RPM.text stringByAppendingString:output]];
}
}
}
}
break;
case NSStreamEventErrorOccurred:
[self.logTextView setText:[self.logTextView.text stringByAppendingString:#"Can not connect to the host!"]];
break;
case NSStreamEventEndEncountered:
break;
default:
NSLog(#"Unknown event");
}
}
- (IBAction)sendCode:(id)sender {
NSString *command = self.commandTextField.text;
NSString *response = [NSString stringWithFormat:#"%#\r\n", command];
NSData *data = [[NSData alloc] initWithData:[response dataUsingEncoding:NSUTF8StringEncoding]];
[self.outputStream write:[data bytes] maxLength:[data length]];
}
#end
I did that tcp connection with help from tutorial from http://www.raywenderlich.com so I don't understand it that much to solve my problem.
This line [self.RPM setText:[self.RPM.text stringByAppendingString:output]]; shows answer in Label but it shows everything. I think I need to create new variable output and edit it somehow but I don't know how