iOS中判断是从哪个控制器push进来的，返回指定控制器

• push将控制器压到栈中，栈是先进后出；pop是出栈：即将控制器从栈中取出。

NSArray*arrController =self.navigationController.viewControllers;

NSIntegerVcCount = arrController.count;

• 返回到指定的控制器：遍历一遍子控制器，判断一下哪个是要返回的控制器，进行返回

UIViewController* back = nil;
    for(UIViewController* vc in self.navigationController.childViewControllers){
        if([vc isKindOfClass:[LegalPersonInformVC class]]){
            back = vc;
            break;
        }
    }
    
    if(back){
        [self.navigationController popToViewController:back animated:YES];
    } else {
        [self.navigationController popToRootViewControllerAnimated:YES];
    }