How to call an NSTimer until selector is successful

Question

I have a function called "Check" that checks if an object has been updated, if that's the case, the user is sent to another view controller. However, the NSTimer keeps repeating itself, I want it to stop after the user is sent to the other view controller.

func check(){
    let current = PFUser.currentUser()?.objectForKey("username")
    let check = PFQuery(className: "Requests")
    check.whereKey("username", equalTo: current!)
    check.whereKey("requestResponded", equalTo: "True")
    check.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
        if error != nil || objects == nil{
            print("Request rejected.")
        } else {
            for object in objects!{
                let service = object["service"] as! NSValue
                print(service)
                if service == 1{
                    self.performSegueWithIdentifier("detailedRequest", sender: self)
                    print("detailedRequest")
                } else {
                    self.performSegueWithIdentifier("normalRequest", sender: self)
                    print("normal")
                }
            }
            print("Successfully retrieved that object.")
        }
    })
}

self.timer = NSTimer.scheduledTimerWithTimeInterval(10.0, target: self, selector: #selector(self.check), userInfo: nil, repeats: true)

Answer 1

Declare a viewDidDisappear function and inside it invalidate your timer. This function automatically be called each time your viewController has disappeared.

Something like this:

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(true)
    self.timer.invalidate()
}