Problem using Category to split a large file

Question

I want to split a large class file by putting methods used only internally into a separate source file. The original file is "Calculator.m"; the new file is "CalculatorP2.m" which has been added to the project. In the main file I have added the statement:
#import "CalculatorP2.m"
just ahead of "@implementation Calculator".
In "CalculatorP2.m I have placed the statements:
#import "Calculator.h"
@interface Calculator ( CalculatorP2 )
@end
@implementation Calculator ( CalculatorP2 )
ahead of the source code. The compiler is happy with this but the linker fails, saying:
/usr/bin/ld: multiple definitions of symbol .objccategory_name_CalculatorCalculatorP2
Any idea as to how to fix this? I am using XCode 2.4.1.

Answer 1

SecondViewControllerP2.h:
#import <UIKit/UIKit.h>
#import "SecondViewController.h"
@interface Secondviewcontroller(SecondviewcontrollerP2)
- (void)method1;
@end
SecondViewControllerP2.m:
#import "SecondViewControllerP2.h"
@implementation Secondviewcontroller(SecondviewcontrollerP2)
- (void)method1 {
NSLog(@"method1");
@end
SecondViewController.m:
#import "SecondViewController.h"
#import "SecondViewControllerP2.h"
@implementation Secondviewcontroller
@end