Delegation - Change variables from different viewsControllers

问题

I have an UIImageView (img) on the container2View as an IBOutlet. How can I change the img.image and refresh the view from other container (containerView)?

We have to use delegation

mainController

class mainController: UIViewController, containerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

        switch segue.identifier! {

            case "container":

            var view = segue.destinationViewController as containerController
            view.delegate = self

            break

            default: break
        }
    }

    func change(name: String) {

        println(name)    //prints the name
        container2Controller().img.image = UIImage(named: "name")   //not seems to work
    }
}

containerController

protocol containerDelegate {

    func change(name: String)
}

class containerController: UIViewController {

    var delegate: containerDelegate?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    @IBAction func click() {

        delegate?.change("hi")    
    }
}

container2Controller

class container2Controller: UIViewController, containerDelegate {

    @IBOutlet var img: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    func change(name: String){

        self.img.image = UIImage(named: name)
    }
}

回答1:

You could handle this by using delegation. Let's say container2 has a button that when pressed should initiate an update to container4.

In Container2, declare a delegate protocol like:

@protocol Container2Delegate
- (void) actionDidOccurInContainer2: (Container2) container2;
@end

and add a property to Container2 class:

@property (weak, nonantomic) id<Container2Delegate> delegate;

Then implement the delegate method in the superContainer, and set Container2s delegate to be the superContainer (in prepareForSegue if you're using storyboards).

In the method implementation, you can update Container4:

- (void) actionDidOccurInContainer2: (Container2) container2 {
     container4.imageView.image = <your image>
}

In container2 you'll have something like:

- (IBAction)doSomething: (id) sender
{
    [self.delegate actionDidOccurInContainer2: self];
}

来源：https://stackoverflow.com/questions/27377011/delegation-change-variables-from-different-viewscontrollers