编译器警告帮助:类型匹配时从不同的objective-c类型初始化

这是我得到编译器警告的函数,我似乎不知道是什么导致了它。感谢您的帮助。

 -(void)displaySelector{
    //warning on the following line:
    InstanceSelectorViewController *controller = [[InstanceSelectorViewController alloc] initWithCreator:self];
    [self.navController pushViewController:controller animated:YES];
    [controller release];
}

initWithCreator的接口和实现:方法

-(InstanceSelectorViewController*)initWithCreator:(InstanceCreator*)creator;


-(InstanceSelectorViewController*)initWithCreator:(InstanceCreator*)crt{
    if (self = [self initWithNibName:@"InstanceSelectorViewController" bundle:nil]) {
        creator = crt;
    }
    return self;
}