How do I become a efficient iOS developer ?

I think you want to become AN efficient IOS developer...

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I thought you just keep paying apple money until you unlock the next chapter or something in the developers portal?

One of the greatest and stupidest things (for solo devs) apple did was force you to pay for the right to learn when the tools are free. I can understand the publish part but to learn is a joke.

@C0D4 Whaaa ? :O
I haven't come across any paid learning material from Apple. They even have a free 900 page book on App development. Are you talking about developer license ?

Here's a good book from Apple themselves (App development with swift) :
https://itunes.apple.com/us/book/...

Drink coffee. Lots of coffee.