Iphone limit memory

I am writing an application for iPhone/iPad and I need to implement a function to allow users to upload pdf. i wonder if there are limits on the 开发者_如何学编程amount of available memory?

Of course there is a limit. The iPhone has no swap file so if you use up all available memory, the OS will kill your app. The amount of RAM on iOS devices currently varies between 128 MB (iPhone 3G and older), 256 MB (iPhone 3Gs, iPad) and 512 MB (iPhone 4 and the newest iPod touch). How much of this is available to your app also varies on the amount the OS consumes.

Available memory to the frontmost app can go down to as little as 10-20 MB.