Run method when viewcontroller is accessed from an

问题:

Let's say I have my initial vc called VC1, then I have a second one called VC2. VC1 has a segue to VC2, on VC2 there is a button that will dismiss VC2 and then show VC1. Once VC1 loads I want to run a method but I can't do that in view did load so where can I do it?

[VC1] -> [VC2]

回答1:

You can use a delegate method to achieve this. In the method you call to dismiss VC2 call the delegate. You can implement this delegate in VC1.

回答2:

You can also try Unwind Segue for dismissing the VC2 and call methods in VC1. It is very easy and requires less coding.

In your VC1 add below method:

@IBAction func unwindToVC1(segue:UIStoryboardSegue){
    print("Hello")
}

In storyboard right click on Exit icon of VC1 and and connect a segue to VC2:

Then in storyboard in VC2 select the unwindSegue and name it :

now in the method where you are dismissing the VC2 just add:

performSegue(withIdentifier: "dismissSegue", sender: self)

you can also pass data from VC2 to VC1.

回答3:

In VC1: Delegate of VC2 and in VC1 Controller in Class or extension

add the delegate method into VC1 that would called after dismiss the VC2

In VC2: Add the protocol of VC1 and make the object of Protocol delegate then its segue exit it goto VC1 Delegate method.

Example:

VC1:

extension VC1, myCustomVC2Delegate {
    func didCloseDelegate() {
        // Your function or method Called here
    }
}

VC2:

protocol myCustomVC2Delegate {
    func didCloseDelegate()
}
import UIKit

class VC2: UIViewController {

    var delegate: myCustomVC2Delegate?

    @IBAction func onTapGotoVC1(_ sender: AnyObject) {
        self.performSegue(withIdentifier: "gotoVC1", sender: self)
    }


    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        if segue.identifier == "gotoVC1" {
           if self.delegate != nil {
            self.delegate?.didCloseDelegate()
        }
     } 
}