Question

Please help, I don’t know what I have to do with didReceiveMemoryWarning exactly. My app launched well, but when there is too many running background apps, it receives memory warning, and exit. I just want to show an alert that asks user to exit some background apps.

I have an appDelegate, in its window there is a view of my viewController, it has another view allocated (composite) with two subviews (a XIB over an OpenGL view), and this is set to be a cameraOverlayView in the viewController.

I tried to release the whole stuff in one at warning, but still exited. Do I have to implement didReceiveMemoryWarning in each subview? Can I somehow “forcequit” the initialization process?

Answer 1

If your app is being terminated while it is active, then you probably have a memory leak causing your app to consume a large amount of memory.

When the OS starts running out of memory it will terminate background tasks first starting with the most memory intensive, then eventually the front-most app. The user never needs to manually terminate background apps to save memory. This is all done automatically.

If your app is in the background then it can be terminated at any time. The best you can do is reduce overall memory usage and hope the OS kills some other more memory intensive apps before yours.

didReceiveMemoryWarning is usually where you would release any cached data you have to try and reduce your app’s footprint. Any view controllers in your app whose view isn’t currently visible will be unloaded and the viewDidUnload method will be called. This is where you should set any IBOutlet properties to nil.

But again if your app is being terminated while it is active, you should use the Leaks tool in Instruments to make sure you don’t have any leaks and you aren’t consuming an abnormally large amount of memory.