Is Swift Pass By Value or Pass By Reference

Question

I\'m really new to Swift and I just read that classes are passed by reference and arrays/strings etc. are copied.

Is the pass by reference the same way as in Objecti

Answer 1

Everything in Swift is passed by "copy" by default, so when you pass a value-type you get a copy of the value, and when you pass a reference type you get a copy of the reference, with all that that implies. (That is, the copy of the reference still points to the same instance as the original reference.)

I use scare quotes around the "copy" above because Swift does a lot of optimization; wherever possible, it doesn't copy until there's a mutation or the possibility of mutation. Since parameters are immutable by default, this means that most of the time no copy actually happens.