How to call a function from another class file
- by Guy Parker
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.
