Add nullability qualifiers for swift integration

[olarivain]

The current iOS headers don't specify any nullability qualifiers. This means that clang will treat everything as implicitly unwrapped, which makes this framework a ticking time bomb to use with Swift.

Objective-c is being relegated to a second class citizen, this kind of thing is an absolute must have for a lot of folks out there.

This has been on my list for a while, but it hasn't made it to the top of the list of TODOs yet. I'm going to take your vote and bump this up in priority for the SDK team.

[olarivain]

thanks!

The workaround I have so far is to manually add nullability on the headers I actually use. Evidently, this isn't great for maintainability, so it'd be really nice to have it in an upcoming release.

[jfricker]

Echoing the desire for full Swift happiness and the end of time bombs. I'm evaluating Tune and Swift support is high on our list. Thank you!

I hear you... I bumped this up, but it is still behind some other work in the queue.