Check out example codes for "swift setinterval". It will help you in understanding the concepts better.

Code Example 1

var helloWorldTimer = Timer.scheduledTimer(timeInterval: 60.0, target: self, selector: #selector(ViewController.sayHello), userInfo: nil, repeats: true)

 @objc func sayHello() 
 {
     NSLog("hello World")
 }

Learn ReactJs, React Native from akashmittal.com