i guess it's hard to write large stable apps in ObjectiveC? I wouldn't like to. Maybe Swift will change things, but it'll take a while, given their legacy.
I'm thinking "Node.js for everything." It's way more fun, more productive, and runs small and fast. Forget threads. I too used to believe "Java for Everything." Over it. Write microservices in Node. Build front-ends in Angular. Talk JSON.
Javascript is great fun to play with in one's browser - you can edit, and reload and voila :)
Recently i've been playing with the HTML5 canvas, drawing sequence diagrams and network diagrams programmatically - and can't remember when i last had so much fun programming - took me back to my teenage years and my first programs, drawing "graphics" on those cathode ray tubes ;)
Being a biased Java developer, i would otherwise recommend Groovy.
They do work for capturing secrets for 2-factor authentication into an app such as Google Authenticator, which implements an ISO OTP standard. Any site with username/password should really generate a OTP secret as QR code to scan into one's phone!