Factory (design pattern) in Objective C

I'm trying to create a factory (design pattern) in Objective C So I'm doing something like:

+ (Car *)createCar:(int)color {
    if (color == 1) {
        return [CarFactory createBlueCar];
    } else if (color == 2) {
        return [CarFactory createRedCar];
    } else {
        return nil;
    }
}

+ (Car *)createBlueCar {
    // ...
}

+(Car*)createRedCar{
    // ...
}

However I don't want the createBlueCar and the createRedCar to be available to public and if I don't define them in the .h file then I get a warning of the missing definition.

I'm a former Java developer and a newbie in Objective-C — So it might be just bad practice If so what the be good practice of doing so.