控制器跳转的代码块

1. 传入要返回的控制器类 [ViewController class],支持返回任意指定的控制器

- (IBAction)goBack:(id)sender {
    [self backAction:[ViewController class]];
}
- (void)backAction:(Class)aClass {
    UINavigationController *nav = self.navigationController;
    NSMutableArray *viewControllers = [NSMutableArray array];
    for (UIViewController *vc in [nav viewControllers]) {
        [viewControllers addObject:vc];
        if ([vc isKindOfClass:aClass]) {
            break;
        }
    }
    [nav setViewControllers:viewControllers animated:YES];
}