UINavigationController

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated;

//使用pop方法可以移除控制器
//将栈顶的控制器移除
- (UIViewController *)popViewControllerAnimated:(BOOL)animated;
//回到指定的子控制器
- (NSArray *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated;
//回到根控制器（栈底控制器）
- (NSArray *)popToRootViewControllerAnimated:(BOOL)animated;

//左上角的返回按钮
@property(nonatomic,retain) UIBarButtonItem *backBarButtonItem;
//中间的标题视图
@property(nonatomic,retain) UIView          *titleView;
//中间的标题文字
@property(nonatomic,copy)   NSString        *title;
//左上角的视图
@property(nonatomic,retain) UIBarButtonItem *leftBarButtonItem;
UIBarButtonItem *rightBarButtonItem
//右上角的视图
@property(nonatomic,retain) UIBarButtonItem *rightBarButtonItem;

    // 清空导航条背景图片,系统判断当前是否为Nil,如果为nil,系统还是会自动生成一张背景图片
    [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
    [self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init]];

//每一个Segue对象，都有3个属性
//唯一标识
@property (nonatomic, readonly) NSString *identifier;
//来源控制器
@property (nonatomic, readonly) id sourceViewController;
//目标控制器
@property (nonatomic, readonly) id destinationViewController;

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender;
// 这个sender是当初performSegueWithIdentifier:sender:中传入的sender

//以Modal的形式展示控制器
- (void)presentViewController:(UIViewController *)viewControllerToPresent animated: (BOOL)flag completion:(void (^)(void))completion

关闭当初Modal出来的控制器
- (void)dismissViewControllerAnimated: (BOOL)flag completion: (void (^)(void))completion;

    //如果一个控制器的View显示在界面上，一定要把这个控制器强引用
    //1. 首先创建一个当前控制器将要跳转到的控制器
    YLViewController *VC = [[YLViewController alloc] init];

    //2.把Modal的控制器的View添加到窗口上，把之前的窗口上的View移除
    UIWindow *keyWindow = [UIApplication sharedApplication].keyWindow;
    [keyWindow addSubview:VC];

    //3.改形变属性，控制一个控件的位置(translation)，尺寸（scale），角度（rotation）
VC.view.transform = CGAffineTransformMakeTranslation(0,self.view.bounds.size.height);

    //4.动画向上推出
[UIView animateWithDuration:0.5 animations:^{
    //CGAffineTransformIdentity:形变全部清空
    VC.view.transform = CGAffineTransformIdentity;
}completion:^(BOOL finished){
    [self.view removeFromSuperview];
}];