why the available free space in the device is changing frequently in iphone sdk?

In my application I'm displaying available free space for my application in the device. The value is changing every time when I launching the application. Why is it happening like this.

Initially my available free space is 30,752,768 bytes and after allocating all the objects the available free memory is :2,809,856 bytes. after this I added some images to the view by using camera option then I received memory warning level = 1 and after that i get free memory space as 12,705,792 by开发者_运维问答tes. Why it is increased like this.

Can any one help me.

Memory warnings trigger a release of unneeded objects. This may include views that are not displayed and intermediary data that does not need to be in memory, especially stuff that can be recreated as needed – perhaps even pre-scaled images.