I suspect the reason is because of the deep system integration of things like Safari, Mail, Contacts, and the like. Take Mail, for example, if you could set Sparrow as your default client on iOS you’d still have to configure Mail because any email sent from other apps uses the Mail API. Then rely on IMAP to sync those things up. Inelegant and un-Apple.
That’s a good point about email, but it doesn’t apply to web browsing. There is no “Safari” sheet in iOS. And even for email, the answer is that iOS should allow third-party apps — like Sparrow — to provide their own system-wide sharing sheets.
Jailbroken iPhones can install a “tweak” from the Cydia store called Sparrow+, which completely replaces Mail system-wide with Sparrow – sharing sheets and all. So it’s evidently possible to do this deep, system-wide integration in some manner. Perhaps Apple needs to find some way of doing this while avoiding a potential privacy PR nightmare, like in the Path/Contacts saga?
The more the iPhone is opened up to third-party apps, the more they receive access to a lot of very personal information, and ultimately any privacy snafus tend to be reported as a problem with the iPhone itself, not the app. This is not something Apple wants. I think if they can solve this conundrum then we’ll be allowed to set different default apps.
- On the Lack of User-Choosable Default Apps in iOS (rampantspeculation.squarespace.com)