[viewController @selector(selector)]将导致编译错误(错误：在’selector’之前预期’：’).

当选择器是硬编码时,一切都很好.

如何通过选择器向对象发送消息？

-(void) notifyViewControllers:(NSString*) message
{
    if(!message) return;

    SEL selector = NSSelectorFromString(message);
    if(!selector) return;

    NSArray* viewControllers = [self.tabBarController viewControllers];
    if(!viewControllers) return;

    for (UIViewController* viewController in viewControllers)
    {
        if(!viewController) continue;

        if ([viewController respondsToSelector:selector]) {
            // [viewController selector];
            [viewController action:selector];
        }
    }
}