自定义导航控制器，统一设置Push的时候隐藏底部的tabbar

#import "NavigationController.h"@interface NavigationController ()@end@implementation NavigationController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.}/** *  重写Push方法(隐藏底部的tabbar) */- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated{    if (self.viewControllers.count) { //避免一开始就隐藏了        viewController.hidesBottomBarWhenPushed = YES;    }    [super pushViewController:viewController animated:animated];}@end