Using an NSTimer in Swift

Question

In this scenario, timerFunc() is never called. What am I missing?

class AppDelegate: NSObject, NSApplicationDelegate {

    var myTimer: NSTimer? = nil

             


        

Answer 1

This is a bit of code, that demonstrates how to call a function (delayed) with AND without a parameter.

Use this in a new project in xCode (singleViewApplication) and put the code into the standard viewController:

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        NSTimer.scheduledTimerWithTimeInterval(2.0, target: self, selector: Selector("delayedFunctionWithoutParameter:"), userInfo: nil, repeats: false)

        let myParameter = "ParameterStringOrAnyOtherObject"

        NSTimer.scheduledTimerWithTimeInterval(4.0, target: self, selector: Selector("delayedFunctionWithParameter:"), userInfo: myParameter, repeats: false)
    }

    // SIMPLE TIMER - Delayed Function Call
    func delayedFunctionWithoutParameter(timer : NSTimer) {
        print("This is a simple function beeing called without a parameter passed")
        timer.invalidate()
    }

    // ADVANCED TIMER - Delayed Function Call with a Parameter
    func delayedFunctionWithParameter(timer : NSTimer) {

        // check, wether a valid Object did come over
        if let myUserInfo: AnyObject = timer.userInfo {
            // alternatively, assuming it is a String for sure coming over
            // if let myUserInfo: String = timer.userInfo as? String {
            // assuming it is a string comming over
            print("This is an advanced function beeing called with a parameter (in this case: \(myUserInfo)) passed")
        }

        timer.invalidate()
    }
}

Notice, that in any case you should implement the delayed function with the parameter (timer : NSTimer) to be able to invalidate (terminate, end) the timer. And with the passend "timer" you have also access to the userInfo (and there you can put any Object, not only String-Objects, as well collection types such as arrays and dictionaries).

Original Apples documentations says "" -> The timer passes itself as the argument, thus the method would adopt the following pattern: - (void)timerFireMethod:(NSTimer *)timer Read fully -> here