Along with many other Mac and iOS developers, I’m digging into Apple’s SDK for tvOS development. As announced in the special event yesterday, the SDK is based on iOS and will be very familiar to most Apple platform developers. There are, however, some differences: functionality from iOS frameworks that is not available on tvOS, as well as a handful of new frameworks specifically suited to the needs of “TV apps.”
A very notable absence is UIWebView. Black Pixel’s Daniel Pasco points out on Twitter that this will be a significant impediment to porting many iOS apps:
FWIW, I'm pretty sure 60% to 80% of the major apps out there use a web view here and there in their apps. So that will be impactful.
— Daniel Pasco (@dlpasco) September 10, 2015
When I say UIWebView is absent, I should clarify that the class name is still present in the UIKit headers on the tvOS SDK, but it is marked with a new compiler availability attribute, __TVOS_PROHIBITED. This is handy because at least when you run up against the problem, you don’t have to fret about whether you simply neglected to link against the right framework. It’s there, it may or may not work, you just can’t use it.
In case it’s not obvious, you can use a massive search of the SDK’s header files to zero in on other such classes and methods that may be prohibited from use in TV apps:
grep -r TVOS_PROHIBITED UIKit.framework/Headers/*
(Note: it was brought to my attention that this search is purely academic because Apple has published a browsable list of API changes from iOS to tvOS.)
The results are a doozy! But many of the marked items simply wouldn’t make sense on Apple TV, like mucking with the UIStatusBar, are marked as prohibited. There are other tags too, such as __TVOS_UNAVAILABLE, which presumably denotes that technologies that Apple would like to provide but hasn’t yet, and __TVOS_DEPRECATED, which blessedly does not yet match any API provided in the tvOS SDK.
Take a look in the Availability.h header file for this and other interesting attribute definitions, including counterparts for OSX, iOS, and watchOS.