NSXMLParserDelegate compile problem - iPhone SDK 30. vs 4.0

[arnieterm]

Hi,
My header file is defined like this:
#import <Foundation/Foundation.h>
@interface Warning: NSObject {
In my .m file I do:
NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL:url];
[parser setDelegate:self];
This compiles and works just fine under 3.1.3
If I try to compile with 4.0 I get this error:
does not implement the 'NSXMLParserDelegate' protocol
If I add:
@interface Warning: NSObject <NSXMLParserDelegate> {
It compiles fine with 4.0, but when I try to compile with 3.1.3 I get:
error: cannot find protocol declaration for 'NSXMLParserDelegate'

The Foundation framework is found correctly. Adding NSXMLParser.h doesn't help.
Any help would be appreciated.

Thanks
Arnie