I am very familiar with writing VB based applications but am new to Xcode (and Objective C). I have gone through numerous tutorials on the web and understand the basics and how to interact with Interface Builder etc. However, I am really struggling with some basic concepts of the C language and would be grateful for any help you can offer. Heres my problem…

I have a simple iphone app which has a view controller (FirstViewController) and a subview (SecondViewController) with associated header and class files.

In the FirstViewController.m have a function defined

@implementation FirstViewController

• (void) writeToServer:(const uint8_t ) buf { [oStream write:buf maxLength:strlen((char)buf)];
  }

It doesn't really matter what the function is.

I want to use this function in my SecondViewController, so in SecondViewController.m I import FirstViewController.h

import "SecondViewController.h"

import "FirstViewController.h"

@implementation SecondViewController

-(IBAction) SetButton: (id) sender {

NSString *s = [@"Fill:" stringByAppendingString: FillLevelValue.text]; NSString *strToSend = [s stringByAppendingString: @":"]; const uint8_t *str = (uint8_t *) [strToSend cStringUsingEncoding:NSASCIIStringEncoding];

FillLevelValue.text = strToSend;

[FirstViewController writeToServer:str];

}

This last line is where my problem is. XCode tells me that FirstViewController may not respond to writeToServer. And when I try to run the application it crashes when this function is called.

I guess I don't fully understand how to share functions and more importantly, the relationship between classes.

In an ideal world I would create a global class to place my functions in and call them as required.

Any advice gratefully received.