Getting ready

Let's see what we can do to avoid this situation. Create a new project in Xamarin Studio and name it EfficientControllerApp.

How to do it…

Perform the following steps to complete this recipe:

How it works...

This project does not provide any useful functionality. Its main purpose is to show how to get notified on memory warnings issued by iOS.

When a memory warning is issued, the DidReceiveMemoryWarning method will be called on all instantiated view controllers that are currently in memory. When this method is called, we should make sure we release the resources that are not currently required. This way, we are making more memory available to the system.

iOS Simulator provides the option of simulating memory warnings so that we can test how our app will behave when memory is low. On a real device, we cannot force the system to issue memory warnings on demand. Note that although we can practically simulate an unlimited number of memory warnings on the simulator, the app will never be terminated. On the other hand, on the device, the app will be terminated after two or three memory warnings (the actual number varies according to memory usage), so we need to take this into account.

There's more...

View controllers are not the only object that can receive memory warnings. We can capture memory warning notifications by overriding the UIApplicationDelegate.ReceiveMemoryWarning(UIApplication) method inside the AppDelegate class, as follows:

public override void ReceiveMemoryWarning(UIApplication application)
{  //...    }

See also