I don't know how Javascript plays into that - I assume Javascript is slower than Swift, but I don't think it is more maintainable.
We're not choosing religions here. Language is a technical decision (with business impact due to hiring availability). You choose the language that fits your goals best, not which one has a better saint.
That's often an abused statement with no actual significance. If you are writing native iOS apps, you basically get two, maybe three, choices.
There is always a group of developers who will rush ahead and there's a group that will lag behind. It has more to do with human nature than the technical features of a language. That's why a year ago I started collecting a bunch of Swift resources in one place. Ive got almost 1500 urls.
http://www.h4labs.com/dev/ios/swift.html
Most blogs/articles on iOS development are now in Swift. If you are learning iOS 9, for example, it's easier to go with Swift. Swift is now the path of least resistance.