Qustion is not about JS and hybrid development.
I'm just learning but if you are ever going to work there will be obj c around for a long time. Me I plan on my own apps so I'm concentrating on Swift. There are tons of tutorials out there just try to build and Google. There are ide's out there but I think Xcode is the way to go. Easy to understand and it's laid out well. It's made for the purpose of building apps so you have it all with no messing around with plug ins which is always a pain in the ass. There are hybrid dev schemes that you can use HTML and CSS like phone gap which I didn't like. On the scene now is React, you might want to look at that considering you have a background there. JavaScript is a must so if you are skilled in that you are well on your way get Atom.io and go go go. It sounds like you have a background so from someone who didn't and took the hard way but sounded like the easy way I would use Xcode and start with Obj c. Then add Swift. I tried circumventing around it and using all the other stuff out there that was supposed to make it easy with what you already know but it all looked like shit. Then again I'm not a pro so maybe I just suck at it. Depending on what you want to build will dictate what libraries ect. Like Facebook Api ect. Hope this helps.
Swift
Apple has a native framework for iOS development, Cocoa Touch. There are other libraries that can be used depending on what you want, but you'll mostly depend on UIKit, which comes with Cocoa Touch, to access native UI functionalities.
Go with Xcode
Xcode comes with a feature called Interface Builder (IB) which, like the name, help you in building interfaces/UI. It's optional, you can create and layout your UI programmatically too. Layout is flexible, but Apple prefers Auto Layout.
Given that you already have an understanding of programming, I'd say go with this course taught by Paul Hegarty, provided by Stanford University on iTunes. It ignores the trivial things and helps you understand the important stuffs real quick, no BS. (I took this same tutorial when I was getting started with iOS development in 2015, but it was based on iOS 8.)
Sidenote: You could also try out React Native, an open-source project by Facebook to build native apps. And, no, this is not a hybrid approach unlike the PhoneGaps and Ionics of the world. Given that you already know Javascript this will get you up fast onto developing your own native Android/iOS apps. And the best part is that you would be able to share more than 80% of your code between Android and iOS depending on your project.