Typically you would write a value to NSUserDefaults to indicate that an app has launched before.
let launchedBefore = NSUserDefaults.standardUserDefaults().boolForKey("launchedBefore")
if launchedBefore {
print("Not first launch.")
}
else {
print("First launch, setting NSUserDefault.")
NSUserDefaults.standardUserDefaults().setBool(true, forKey: "launchedBefore")
}
UPDATE – Swift 3
let launchedBefore = UserDefaults.standard.bool(forKey: "launchedBefore")
if launchedBefore {
print("Not first launch.")
} else {
print("First launch, setting UserDefault.")
UserDefaults.standard.set(true, forKey: "launchedBefore")
}