iPhone – How does IOS decide which objects DidRecEMemoryWarning message?

Simulation in the simulator When a low memory error occurs, I found that not all view controllers receive the didReceiveMemoryWarning notification. Unfortunately, these are the controllers that are most conducive to implementing this method.

I can’t seem to find out where the method is called And good information on the way. I have read mentioning that it is sent to “all UIViewControllers”, but it is not. Adding a breakpoint in one of the classes that receives notifications is not particularly instructive.

This is a complicated project, but there are ways to add these views:

- (void) showMyView
{
 if(!myViewController){ 
 myViewController = [[MyViewController alloc]init];
 [window addSubview:myViewController.view];
 }
}

MyViewController is another class MySuperViewController It is a subclass of UIViewController itself. None of these classes have a corresponding NIB; the view hierarchy is created programmatically.

I am looking for instructions on how to diagnose the problem.

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I am developing an iPhone application where many UIViews are dynamically added to the main UIWindow And removed from the main UIWindow.

When simulating a low memory error in the simulator, I found that not all view controllers receive the didReceiveMemoryWarning notification. Unfortunately, these are the most beneficial for implementation The controller for this method.

I can’t seem to find good information about where and how the method is called. I have read mention that it is sent to “all UIViewControllers”, but it is not the case. In it Adding breakpoints to a notification-receiving class is not particularly enlightening.

This is a complex project, but the ways to add these views are:

< pre>– (void) showMyView
{
if(!myViewController){
myViewController = [[MyViewController alloc]init];
[window addSubview:myViewController.view];< br /> }
}

MyViewController is a subclass of another class MySuperViewController, which itself is a subclass of UIViewController. None of these classes have a corresponding NIB; the view hierarchy is created programmatically.

I am looking for instructions on how to diagnose the problem.

When you use the view controller’s .view directly, the view controller It is very likely that you will not receive many notifications because it is not the correct way to use the view controller. UIWindow is a special case because the window can automatically know the view controller and correctly direct the message to the controller.

However, when you detach the view from the UIWindow, the view controller is also detached and is no longer managed by the UIWindow. I think this is the source of the problem.

I suggest you add a navigation controller or label The bar controller acts as the root view controller and uses the view controller function to switch between your child controllers. Please note that view controllers should not be deleted when switching so that they can receive messages correctly.

< p>If the initialization of the view controller is simple and does not consume too much time, you may also consider releasing the view controller when not in use.