iOS Delegate concept explained : Shubham Mishra

#Here's a little help on delegates between two view controllers:

#Step 1: Make a protocol in the UIViewController that you will be removing/will be sending the data.
protocol FooTwoViewControllerDelegate:class {
    func myVCDidFinish(_ controller: FooTwoViewController, text: String)
}



#Step2: Declare the delegate in the sending class (i.e. UIViewcontroller)
class FooTwoViewController: UIViewController {
    weak var delegate: FooTwoViewControllerDelegate?
    [snip...]
}



#Step3: Use the delegate in a class method to send the data to the receiving method, which is any method that adopts the protocol.
@IBAction func saveColor(_ sender: UIBarButtonItem) {
        delegate?.myVCDidFinish(self, text: colorLabel.text) //assuming the delegate is assigned otherwise error
}



#Step 4: Adopt the protocol in the receiving class
class ViewController: UIViewController, FooTwoViewControllerDelegate {}



#Step 5: Implement the delegate method
func myVCDidFinish(_ controller: FooTwoViewController, text: String) {
    colorLabel.text = "The Color is " +  text
    controller.navigationController.popViewController(animated: true)
}



#Step 6: Set the delegate in the prepareForSegue:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "mySegue" {
        let vc = segue.destination as! FooTwoViewController
        vc.colorString = colorLabel.text
        vc.delegate = self
    }
}