How to keep an application open counter inside the application?

Question

iOS

How to keep a counter of the number of application openings inside the application, to further implement the user's progress based on the number of entrances to the application?

Answer 1

NSUserDefaults to help
Update:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        
        ...
        let userDefaults = NSUserDefaults.standardUserDefaults()
        if var numberOfLaunches = userDefaults.objectForKey("numberOfLaunches") as? Int {
            numberOfLaunches++
            userDefaults.setInteger(numberOfLaunches, forKey: "numberOfLaunches")
        } else {
            let n = 1
            userDefaults.setInteger(n, forKey: "numberOfLaunches")
        }
        print(userDefaults.objectForKey("numberOfLaunches") as! Int)
        
        return true
    }