Question

Intro to IOS development question:

6) A Timer class has a schedule method with the following method signature: class Timer func schedule( interval: Double, // in seconds repeats: Bool, callback: Void Explain why a method for scheduling a recurring timer might have a callback parameter as an argument. Create a timer instance that prints the date every 5 seconds. To get the current date use Date ) a) b)

Answer 1

a) The callback parameter is so that we can call a function and ask for another function to be called in X milliseconds. When we pass a callback function as an argument to another function, the callback is executed at some point inside the containing function's body just as if the callback were defined in the containing function.

b) Below is the instance created in java to achieve the fucntionality described above.

import java.util.Timer;

import java.util.Date;

import java.util.TimerTask;

class Helper extends TimerTask

{

    public static int i = 0;

    public void run()

    {

      Date date = new Date();
      System.out.println(date.toString());

}

}

public class Test

{

    public static void main(String[] args)

{

        Timer timer = new Timer();

        TimerTask task = new Helper();

        timer.schedule(task, 0, 5000);

    }

}

Happy coding!