q.m

int main(int argc, char **argv)
{
    return 0;
}

#import <Foundation/Foundation.h>

@interface Foo : NSObject
-(id)newFoo;
@end

@implementation Foo
-(id)newFoo;
{
    return self;
}
@end

works.m

#import <Foundation/Foundation.h>

@interface Foo : NSObject
-(id)newFoo;
@end

@implementation Foo
-(id)newFoo;
{
    return self;
}
@end

int main(int argc, char **argv)
{
    return (int)[[[Foo alloc] init] newFoo];
}