Ok I don't know a lot about iOS development or ARM development in general, but there's something I don't understand. I had the impression that the ARM architecture uses a memory paging system not unlike the one used by x86. This would imply that memory fragmentation shouldn't be an issue, unless we're talking about in-process logical memory address space fragmentation, which would be largely the developer's fault anyway. Am I missing something here?
I haven't done any real investigation on the whole thing, but the general feeling I get about the whole thing is that over time, system-related processes may hold on to more and more memory. I don't know what specifically is doing it or why it's doing it, but the end result is that trying to load a 2048x2048 pixel image will work one time and the next time your app will get killed for it.
iOS devices have NO virtual memory at the OS level. Once it's out of physical RAM, that's when it really begins to clamp down on app memory usage. There's only 256 MB of RAM on the iPad, so loading that one image needs at least 40 MB of that. If a bunch of the Apple-originated processes are resident in memory, and it seems like it hangs on to a bunch of them even after the app is closed, then it may or may not let you use that much memory.
