NSTimers

Welcome to a VERY simple blog post, also my first tutorial!

This time, I will be teaching you how to use something called an "NSTimer".

These are the very useful applications of the NSTimer:

- Repeating a block of code over and over
- Checking for updates from a web server
- Creating a timer
- Checking variables, repeatedly
- Executing a block of code after a time delay

etc.

Let's see how to create a function for the Timer (just a simple Swift function, that will print "Hello World"):

func printHelloWorld() {
    print("Hello World")
}

Next, let's see how we can start the timer:

var timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: "printHelloWorld", userInfo: nil, repeats: true)

The above timer will call the "printHelloWorld" function every 2 seconds.

You can also create a timer, without starting it:

var timer = NSTimer(timeInterval: 2, target: self, selector: "printHelloWorld", userInfo: nil, repeats: true)

The above timer will take all variables into account, but to start it, you must add it to Swift's "Run Loop":

NSRunLoop.currentRunLoop().addTimer(timer, forMode: NSRunLoopCommonModes)

That will start the loop.

No matter what method you choose of starting the timer, you always end it like so:

timer.invalidate()

That's it for this simple tutorial! If you have any more questions or suggestions, please email me at: tajymany@gmail.com

Hope you learned something new and enjoyed it!