π in Swift
I think I'm pretty much doing pi approximations in every language now, so, here it is in Swift! By the way, compare this to Kotlin and see why Kotlin is starting to take over Java in Android development (Swift is for Mac and iOS development).
Here are the other approximations so far:
C# - https://repl.it/talk/share/p-in-C/36141
Bash - https://repl.it/talk/share/p-in-Bash/36133
Kotlin - https://repl.it/talk/share/p-in-Kotlin/36125
Ruby - https://repl.it/talk/share/p-in-Ruby/34982
Java - https://repl.it/talk/share/p-in-Java/34978
QBasic - https://repl.it/talk/share/p-in-QBasic/34973
Fortran - https://repl.it/talk/share/p-in-Fortran/34890
APL - https://repl.it/talk/share/p-in-APL/34888
Forth - https://repl.it/talk/share/p-in-Forth/34652
LOLCODE - https://repl.it/talk/share/p-in-LOLCODE/34421
Python and Node.js (Node is linked in post) - https://repl.it/talk/share/2-Approximations-of-p-In-Only-Four-Lines-of-Code/32773
C - https://repl.it/talk/share/p-Approximations-in-C/33461
Credit to @NoelBryan, @TheForArkLD , @Warhawk947 , and @LizFoster for inspiring these approximations. Most of these use the Nilakantha Series, although I also use the arctangent method (multiplying the radian arctangent of 1 by 4 to get pi and getting the arctangent with an infinite series) in three of them (Python, Node, and C).
Also, thank you to @HahaYes for inspiring this approximation to be done in Swift after attempting your own version with a binary search algorithm!