Expected Identifier or "(" before "{" token - xcode

Question

Somehow I got this error in XCode 4.0.2, not sure what is wrong.
File: HomeViewController.h
#import <UIKit/UIKit.h>
#interface HomeViewController : UIViewController <UITabBarDelegate>
{
UIButton *Button1, *Button2, *Button3;
}
#property (nonatomic, retain) IBOutlet UIButton *Button1;
#property (nonatomic, retain) IBOutlet UIButton *Button2;
#property (nonatomic, retain) IBOutlet UIButton *Button3;
.... other member functions...
....
#end
File: HomeViewController.m
......
#import "RemoteServiceManager.h"
#interface HomeViewController()
{ //This is where the error happens: Expected Identifier or "(" before "{" token
RemoteServiceManager* serviceManager;
}
#end
#implementation HomeViewController
#synthesize Button1, Button2, Button3;
.... other member functions
....
#end
Looks like it does not recognize RemoteServiceManager. Wherever I used the serviceManager, it will say HomeViewController has no member named serviceManager.
Is it possible that is caused by XCode version? I am using XCode 4.0.2 on Mac OS X 10.6.7.
Thanks.

Answer 1

you cant add instance variables to private categories.
put properties in there instead, and synthesize them to obtain a variable as well as an internal getter/setter
#interface HomeViewController
#property (nonatomic, strong) NSString *privateProperty;
#end
#implementation HomeViewController
#synthesize privateProperty = _privateProperty;
#end
or you can add the instance variable to the class itself.
#implementation HomeViewController
NSString *privateVariable;
#end
Bear in mind also. that if you create a category in another file, any variables you declare in the body of that category will be static across all instances. definitely something to keep an eye out for.
To recap. you can create a variable in the interface of the main category. or in the implementation of the main category.
and the private category is for you to add prototypes to your class that will let the rest of the file know they "will be/are" available.

Answer 2

the old xcode cant do this, no. it does know class extensions yet because it ships with an older version of the LLVM compiler

Answer 3

You probably found your answer, but I post the answer here for somebody who encounters the same problem:
as Daij said, the problem is due to the version of compiler, so to fix this you need to change the compiler setting:
Build Setting > Build Options > Compiler for C/C++/ObjectiveC
Change value from "LLVM GCC 4.2" to "Apple LLVM compiler 4.2"
Hope it helps.