Responding to Display-Related Notifications

响应跟显示相关的通知

When the visibility of a view controller’s view changes, the view controller calls some built-in methods to notify subclasses of the changes. You can override these methods to override how your subclass reacts to the change. For example, you can use these notifications to change the color and orientation of the status bar so that it matches the presentation style of the view that is about to be displayed.

当一个视图控制器的视图可见性发生改变时,视图控制器调用一些内建的方法来通知子类发生的改变。 你可以重写(override)这些方法来实现(override)你的子类如何对改变做出反应。 比如,你可以使用这些通知来改变状态栏的颜色和方向,使其跟即将显示的视图风格相配套。

Responding When a View Appears

一、当视图显示时做出响应

Figure 5-1 shows the sequence of events that occurs when a view controller’s view is added to a window’s view hierarchy. The viewWillAppear: andviewDidAppear: methods give subclasses a chance to perform any additional actions related to the appearance of the view.

图5-1 显示了当一个视图控制器中的视图被添加到一个窗口视图层次里发生的一些列事件。 viewWillAppear: 方法 和 viewDidAppear: 方法让子类执行跟视图显示(appearance)相关的任何附加操作。

Figure 5-1  Responding to the appearance of a view

图 5-1 对一个视图的显示(appearance)做出响应

Responding When a View Disappears

二、当视图消失时做出响应

Figure 5-2 shows the sequence of events that occurs when a view is removed from its window. When the view controller detects that its view is about to be removed or hidden, it calls the viewWillDisappear: and viewDidDisappear: methods to give subclasses a chance to perform any relevant tasks.

图5-2 显示了当一个视图从窗口移除时所发生的一系列事件。 当视图控制器检测到其视图即将被删除或隐藏时,它调用  viewWillDisappear: 和 viewDidDisappear: 方法来让子类执行任何相关任务。

Figure 5-2  Responding to the disappearance of a view

图 5-2 响应一个视图的消失

Determining Why a View’s Appearance Changed

三、确定一个视图的显示状态改变的原因

Occasionally, it can be useful to know why a view is appearing or disappearing. For example, you might want to know whether a view appeared because it was just added to a container or whether it appeared because some other content that obscured it was removed. This particular example often appears when using navigation controllers; your content controller’s view may appear because the view controller was just pushed onto the navigation stack or it might appear because controllers previously above it were popped from the stack.

有时候,知道一个视图出现或消失的原因很有用。 比如,你可能因为一个视图e刚刚被添加到一个容而器想要知道它是否被显示,或者因为遮盖(obscured)这个视图的一些内容被移除了而想知道该视图是否被显示。 该特殊例子经常在使用导航控制器时出现;你的内容控制器中的视图可能在视图控制器刚被压入导航栈时出现,或者它可能因为前一个控制器被弹出栈而出现。

The UIViewController class provides methods your view controller can call to determine why the appearance change occurred. Table 5-1 describes the methods and their usage. These methods can be called from inside your implementation of the viewWillAppear:viewDidAppear:viewWillDisappear: andviewDidDisappear: methods.

UIViewController 类提供了一些方法可以让视图控制器调用来确定显示状态(appearance)发生改变的原因。 表格5-1 描述了这些方法以及它们的用途。 这些方法能从viewWillAppear: 和 viewDidAppear: 方法内部调用。

Table 5-1  Methods to call to determine why a view’s appearance changed

Method Name

Usage

isMovingFromParentViewController

You call this method inside your viewWillDisappear: and viewDidDisappear: methods to determine if the view controller’s view is being hidden because the view controller was removed from its container view controller.

你可以在viewWillAppear: 和 viewDidAppear: 方法内部调用该方法,来确认视图控制器的视图是否正被隐藏,原因是视图控制器被从其容器视图控制器中删除。

isMovingToParentViewController

You call this method inside your viewWillAppear: and viewDidAppear: methods to determine if the view controller’s view is being shown because the view controller was just added to a container view controller.

你可以在viewWillAppear: 和 viewDidAppear: 方法内部调用该方法,来确定视图控制器的视图是否正被显示,因为视图控制器刚刚被加入到一个容器视图控制器。

isBeingPresented

You call this method inside your viewWillAppear: and viewDidAppear: methods to determine if the view controller’s view is being shown because the view controller was just presented by another view controller.

你可以在viewWillAppear: 和 viewDidAppear: 方法内部调用该方法来确定视图控制器中的视图是否正被显示,因为视图控制器正被另一个视图控制器呈现(present).

isBeingDismissed

You call this method inside your viewWillDisappear: and viewDidDisappear: methods to determine if the view controller’s view is being hidden because the view controller was just dismissed.

你可以在viewWillAppear: 和 viewDidAppear: 方法内部调用该方法来确定视图控制器的视图是否正被隐藏,因为视图控制器刚刚被释放(dismissed)

View Controller Programming Guide for iOS---(六)---Responding to Display-Related Notifications的更多相关文章

  1. View Controller Programming Guide for iOS---(二)---View Controller Basics

    View Controller Basics Apps running on iOS–based devices have a limited amount of screen space for d ...

  2. View Controller Programming Guide for iOS---(七)---Resizing the View Controller’s Views

    Resizing the View Controller’s Views A view controller owns its own view and manages the view’s cont ...

  3. View Controller Programming Guide for iOS---(一)---About View Controllers

    About View Controllers View controllers are a vital link between an app’s data and its visual appear ...

  4. View Controller Programming Guide for iOS---(四)---Creating Custom Content View Controllers

    Creating Custom Content View Controllers 创建自定义内容视图控制器 Custom content view controllers are the heart ...

  5. View Controller Programming Guide for iOS---(三)---Using View Controllers in Your App

    Using View Controllers in Your App Whether you are working with view controllers provided by iOS, or ...

  6. View Controller Programming Guide for iOS---(五)---Resource Management in View Controllers

    Resource Management in View Controllers View controllers are an essential part of managing your app’ ...

  7. View Controller Programming Guide for iOS---(八)---Using View Controllers in the Responder Chain

    Using View Controllers in the Responder Chain 响应链中使用视图控制器 View controllers are descendants of the UI ...

  8. View Controller Programming Guid for iOS 笔记

    1.View Controller 基础 1.1 View Controller 分类 ViewController分为container view controller 和content view ...

  9. View Programming Guide for iOS ---- iOS 视图编程指南(四)---Views

    Views Because view objects are the main way your application interacts with the user, they have many ...

随机推荐

  1. Shannon-Fano-Elias编码的C语言实现

    Shannon-Fano-Elias编码 一.理论分析 Shannon-Fano-Elias编码是利用累积分布函数来分配码字. 不失一般性,假定取X={1,2,-m}.如果对于全部的x,有p(x)&g ...

  2. c++中vector向量几种情况的总结(向量指针,指针的向量)

    1.标准库vector类型 vector 是同一种类型的对象的集合.每一个对象都有一个相应的整数索引值.标准库将负责管理与存储元素相关的内存.我们把 vector 称为容器,是由于它能够包括其它对象. ...

  3. 重装系统(Win)

    有朋友问我,重装系统该怎样操作呢? 1. 硬盘重装 官网:http://www.heiyunwang.com/ ,点击下载软件:http://dlsw.baidu.com/sw-search-sp/s ...

  4. 【Mongodb教程 第十九课 】PHP与MONGODB的条件查询

    与普通的关系型数据库类似,在对数据的删.改.查的时候,会用到查询条件,如mysql中的 where… 而MongoDB中,经过php来做的所有的操作指令都是用array来包裹的: MongoColle ...

  5. OpenStack IceHouse版cinder模块新添加功能

    感谢朋友支持本博客.欢迎共同探讨交流.因为能力和时间有限.错误之处在所难免,欢迎指正! 假设转载,请保留作者信息. 博客地址:http://blog.csdn.net/gaoxingnengjisua ...

  6. 读懂这些spring boot的核心注解,快速配置完成项目搭建

    在spring boot中,摒弃了spring以往项目中大量繁琐的配置,遵循约定大于配置的原则,通过自身默认配置,极大的降低了项目搭建的复杂度.同样在spring boot中,大量注解的使用,使得代码 ...

  7. openwrt: patch-dtb

    dts的概念是linux kernel中的,跟openwrt的关系不大.只是恰好在学习openwrt的时候碰到了这个东西,所以记录在openwrt名下. patch-dtb openwrt对arch/ ...

  8. hibernate工作原理及作用

    转载自 http://www.cnblogs.com/dashi/p/3597969.html#commentform JAVA Hibernate工作原理及为什么要用 hibernate 简介:hi ...

  9. AOP和OOP的区别

    AOP为Aspect Oriented Programming的缩写,意为:面向切面编程,通过预编译方式和运行期动态代理实现程序功能的统一维护的一种技术. AOP与OOP是面向不同领域的两种设计思想. ...

  10. Chrome浏览器 js 关闭窗口失效解决方法

    //获取元素ID var DelHtml = document.getElementById("imgdel"); //alert(DelHtml); //添加点击事件 DelHt ...