Skimming through it has been great. It's quite well-written and you'll get a lot of the concepts that the lang introduces even if the extent of your programming education is JS. Give it a try :)
Re:Introducing Swift
by josephjrobison on Monday June 02, 2014 @06:48PM
(#7836995)
And is this the exact same language - http://www.cs.cornell.edu/jif/swift/doc/index.html
Honestly skimming 500 doesn't sound horribly hard to me. I've done that a few times to pick up something new. As ap said you won't learn the language like that but you will have a good reference to go and learn from after the fact.
After that you could probably work through the examples in said book, or at least the interesting ones.
P.S. above steps is all I really learnt from my cs degree.