Making some code only run once

Question

I have some code that I would like to run only once in my MainViewController. It should run every time the user starts the app, but only after the MainViewController has loa

Answer 1

for Swift2.2,Xcode 7.3:

static var token: dispatch_once_t = 0

dispatch_once(&YourClassName.token) {
  NSLog("Do it once")
}

Watch out "YourClassName.token"