iOS開發：視圖生命週期

 

iOS應用的視圖狀態分爲如下幾種

• 在viewcontroller的父類UIViewController中能夠看到以下代碼，經過重寫不一樣的方法對操做視圖渲染。

@available(iOS 2.0, *)
public class UIViewController{
 
　　 public func viewDidLoad() // Called after the view has been loaded. For view controllers created in code, this is after -loadView. For view controllers unarchived from a nib, this is after the view is set.
　　 public func viewWillAppear(animated: Bool) // Called when the view is about to made visible. Default does nothing
    public func viewDidAppear(animated: Bool) // Called when the view has been fully transitioned onto the screen. Default does nothing
    public func viewWillDisappear(animated: Bool) // Called when the view is dismissed, covered or otherwise hidden. Default does nothing
    public func viewDidDisappear(animated: Bool) // Called after the view was dismissed, covered or otherwise hidden. Default does nothing
public func didReceiveMemoryWarning() // Called when the parent application receives a memory warning. On iOS 6.0 it will no longer clear the view by default.
 
}

• • viewDidLoad():視圖被加載到內存中時調用viewDidLoad方法，在該方法中可對視圖上佈局進行調整
  • viewWillAppear():視圖可見前
  • viewDidAppear():視圖已經可見，頁面渲染完成後能夠加載一些控件動畫
  • viewWillDisappear():視圖失去焦點前
  • viewWillDidDisappear()：視圖失去焦點後
  • didReceiveMemoryWarning():在iOS 6以後可以使用此方法釋放內存，包括視圖控制器中的一些成員變量