The View management cycle

The View management cycle

Load cycle

1 Some part of your application asks for the view in controller's View property.

2 If the view is not currently in memory, the view controller calls its loadView              

  method.

3 The loadView method does one of the following:

    # If you override this method, your implementation is responsible for creating all necessary views and assigning a non-nil value to the view property.

    # If you do not override this method, the default implementation uses the nibName and nibBundle properties of the view controller to try to load the view from the specified nib file. If the specified nib file is not found, it looks for a nib file whose name matches the name of the view controller class and loads the file.

    # If no nib file is available, the method create an empty UIView object and assigns it the view property.

4 The view controller calls its viewDidLoad method to perform any additional load-time tasks.



Unload cycle

1 The application receives a low-memory warning from the system.

2 Each view controller calls its didReceiveMemoryWarning method:

    # If you override the method, you should use it to release any custom data the your view controller object no longer needs. You should not use it to release your view controller's view. You must call super at some point in your implementation to perform the default behavior.

    # The default implementation releases the view only if it determines that it is safe to do so.

3 If the view controller releases its view, it calls its viewDidUnload method. You can override this method to perform any additional cleanup required for your views and view hierarchy.



   If you retain any view objects using properties or custom setter methods, you should always remember to implement a viewDidUnload method to set those property to nil

        - (void) viewDidUnload{}           - (void) dealloc{}