If you are in the iPhone mobile app development industry then you know that you don’t need to have everything regarding Swift at the top of your head or any language for that matter. But you should understand the basic syntax, optionals, control flow, classes, initialization and air handling.

There are many different places to learn Swift, you can use Apple’s own Swift book which changes because Swift is a newer language. You can also invest in something like iOS development course on Udacity and can also have a membership to Pruralsight.