Conform to new swiftlint rules

[justinswart]

The latest swiftlint introduced some new rules, this PR just addresses them.

Most notable new rule is discarded_notification_center_observer. Turns out all of our block/closure Notification observers were leaking?

Most of the others are fairly innocuous but nice to have them tidied up.

[justinswart]

I've disabled this here seeing as AppDelegate lives forever?

[mbrandonw]

Most notable new rule is discarded_notification_center_observer. Turns out all of our block/closure Notification observers were leaking?

This isn't needed in iOS 9+. From https://developer.apple.com/library/content/releasenotes/MacOSX/WhatsNewInOSX/Articles/MacOSX10_11.html:

NSNotificationCenter and NSDistributedNotificationCenter no longer send notifications to registered observers that may be deallocated. If the observer is able to be stored as a zeroing-weak reference the underlying storage stores the observer as a zeroing weak reference. Alternatively, if the object cannot be stored weakly (because it has a custom retain/release mechanism that would prevent the runtime from being able to store the object weakly) the object is stored as a non-weak zeroing reference. This means that observers are not required to un-register in their deallocation method.

[mbrandonw]

cool, we can revert all the notification center stuff and disable the rule in our swiftlint.

then this should be good to go

[justinswart]

Ah, I should read the docs occasionally :)