zoukankan      html  css  js  c++  java
  • (转载)UIViewController lifecycle

    The UIViewController object is one of the most used objects available in the iOS SDK. It’s important to understand the lifecycle events of this controller and know how we should use them. We are going to focus on the events used toload a view.

    > Lifecycle events order

    1. - (void)loadView
    2. - (void)viewDidLoad
    3. - (void)viewWillAppear
    4. - (void)viewWillLayoutSubviews
    5. - (void)viewDidLayoutSubviews
    6. - (void)viewDidAppear

    > How can we use them?

    - (void)loadView — Creates the view that the controller manages.

    It’s only called when the view controller is created and only when done programatically. You can override this method in order to create your views manually.

    - (void)viewDidLoad — Called after the controller’s view is loaded into memory.

    It’s only called when the view is created. Keep in mind that in this lifecycle step the view bounds are not final. Good place to init and setup objects used in the viewController.

    - (void)viewWillAppear:(BOOL)animated — Notifies the view controller that its view is about to be added to a view hierarchy.

    It’s called whenever the view is presented on the screen. In this step the view has bounds defined but the orientation is not applied. This event is called every time the view appears so don’t add code here which should be executed just one time (or manage it correctly).

    - (void)viewWillLayoutSubviews — Called to notify the view controller that its view is about to layout its subviews.

    This method is called every time the frame changes like for example when rotate or it’s marked as needing layout. It’s the first step where the view bounds are final. If you are not using autoresizing masks or constraints and the view size changes you probably want to update the subviews here.

    - (void)viewDidLayoutSubviews — Called to notify the view controller that its view has just laid out its subviews.

    Make additional changes here after the view lays out its subviews.

    - (void)viewDidAppear:(BOOL)animated — Notifies the view controller that its view was added to a view hierarchy.

    Good place to perform additional tasks associated with presenting the viewlike animations. This method is executed after the animation displaying the view finishes so in this step the view is already visible for the user. In some cases can be a good place to load data from core data and present it in the view or to start requesting data from a server.

     

    转载自:https://medium.com/@SergiGracia/ios-uiviewcontroller-lifecycle-261e3e2f6133

  • 相关阅读:
    贝云cms内容管理系统(thinkphp5.0开源cms管理系统)
    NGINX.conf配置文件支持pathinfo
    阿里云视频直播PHPSDK接入教程
    如何在Nginx下配置PHP程序环境
    tomcat 内存参数优化示例
    12组免费的CSS3按钮强力推荐 狼人:
    9款jQuery插件为你的网站增加亮点 狼人:
    TUP第11期:腾讯、豆瓣精英实例诠释互联网研发之道 狼人:
    【TUP第11期】腾讯黄朝兴:浅谈客户端架构 狼人:
    Linus Torvalds:回顾Linux20年 狼人:
  • 原文地址:https://www.cnblogs.com/scaptain/p/4118654.html
Copyright © 2011-2022 走看看