Swift is slowly moving towards binary and source stability. Storyboards are more capable then they used to be–and they're literally XML. How can you make that unreadable?
Swift devs keep saying it'll get less fragile, then they rewrite "exceptions", or how strings work, or anything else and all your code has to be fixed line-by-line. I do not believe it'll be stable this decade.
Xcode stops supporting old features in XIB, or a class has a deprecated and then removed property, and the deserialization fails. XIB is not XML with a nice semantic DTD, it's an object serialization graph that happens to use XML.
Nah, I switched to Swift at v1.0, the transitions have been relatively easy. Right now our app has 90k lines of code so Swift 3 was a day of work, but mostly automated.
Swift 4 is automatic. The trick to making the transitions easy is to not abuse the language with too clever code. Write clear, straightforward and easily msinatainavle code and it will rarely be broken.
Ask Apple, who hide it from you in Xcode and riddle it with human-unreadable generated IDs and noise elements, in addition to needless reshuffling of elements after editing which overcomplicate your diffs and obscure the meaning of changes. Interface Builder in all its forms is indefensibly bad in execution.
Xcode stops supporting old features in XIB, or a class has a deprecated and then removed property, and the deserialization fails. XIB is not XML with a nice semantic DTD, it's an object serialization graph that happens to use XML.