I am just trying to work out how the viewContro开发者_C百科ller is working in a simple iPhone app. My question is I am trying to see when the functions below get called, I have put NSLog commands in there to print to the console, but I don't see any of the below printing either when running or exiting my app, do they get called, should I see anything?

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
    NSLog(@"-1-");
}

- (void)viewDidUnload {
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
    NSLog(@"-2-");
    self.statusText = nil;
}

- (void)dealloc {
    NSLog(@"-3-");
    [statusText release];
    [super dealloc];
}

EDIT_001:

-1- didReceiveMemoryWarning (as noted by Kenny) works via Hardware>Simulate Memory Warning

-2- I can see why this one is not working now, thank you.

-3- dealloc, I am quiting the running app using the white square at the bottom, does this do a full quit where I should see the NSLog from dealloc?

gary

to answer your question:

• (void)didReceiveMemoryWarning won't fire while running just a simple application. You can test it by loading a bunch of retained objects (like images).

• (void)viewDidUnload : as stated in the comment it only fires if you've got another view attached to your main view.

• (void)dealloc : well, here you should see something. don't know why. did you check the Console of XCode?!

- (void)didReceiveMemoryWarning

is sent to the view controller when the application receives a memory warning (your app gets low on RAM). You can simulate it by selecting Hardware->Simulate Memory Warning in the Simulator.

- (void)viewDidUnload

is called when the controller’s view is released from memory. It is called during low-memory conditions when the view controller needs to release its view.

- (void)dealloc

is sent after the object is released to free the memory it occupies.

I hope this helps.