[rubiquity]

And yet you've managed to shed no light on how constants should be used in Swift.

[andrewmunsell]

To shed some light on the practice of using `let` vs. `var`, an excerpt from the book by Apple:

“If a stored value in your code is not going to change, always declare it as a constant with the let keyword. Use variables only for storing values that need to be able to change.”

Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. https://itun.es/us/jEUH0.l

[jquave]

Thanks Andrew, I am updating the posts as I learn more. We're all still learning.

[gress]

Let is fine for defining constants, but it should also be used whenever possible for two reasons:

1. It gives you additional safety against accidental reassignment.

2. It gives the compiler a major optimization hint since the value is not a variable.

[Jweb_Guru]

The latter isn't really true when it comes to local variables. Compilers are pretty good at figuring that sort of thing out these days.

[gress]

It is one of the reasons stated by Apple at today's WWDC session.