A file system isn't the greatest design from a security standpoint, but the Apple model is particularly limiting if, for instance, you want a library of data to

A file system isn't the greatest design from a security standpoint, but the Apple model is particularly limiting if, for instance, you want a library of data to be available to one app, and then later available to another app. You'll notice the iPhone cheats in this regard, by providing generic system libraries for photos and contacts, but if you say, have an ebook library, and want to switch reader apps, you'll have a bad time. It would probably be better to have a system of secure file buckets, where you could create them arbitrarily and choose to allow access to any bucket to any app, rather than permit open access to the file system as Android traditionally has done.