如何在swift中的nib类之间使用协议委托？

Question

i have one view controller that it has two sub view of nib files. my first nib name is citycollection and secend is currentxib that both of them are UIVIEW. in citycollection view i have collectionview that i want when i click on item of that, print the data i send by protocol in the label of currentxib class.( attention both of them are UIView and not view controller.) but it not work. my main view controller class is empty still. this is my code:

CityCollection class:

///// CityCollection

class CityCollection: UIView, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {

    weak var delegate: sendDataDelegate?

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

        let fName = Publics.instance.getCities()[indexPath.row].fName

        delegate?.name(data: fName)

    }

}



protocol sendDataDelegate : NSObjectProtocol {
    func name(data : String)
}

CurrentXib class :

////CurrentXib
class CurrentXib: UIView, sendDataDelegate {


    func name(data: String) {
        lblCityName.text = data
    }


    @IBOutlet weak public var lblCityName: UILabel!



    override func awakeFromNib() {

        let myCity = CityCollection()
        myCity.delegate = self
    }
}

what should i do?

Answer 1

The problem is here:

    let myCity = CityCollection() // <-- this is the problem
    myCity.delegate = self

All you do here is create a new instance of the CityCollection class. You set that instance's delegate in the next line. And then... myCity , your CityCollection object, vanishes in a puff of smoke. So those two lines are useless.

What you probably meant to do was to obtain, somehow, a reference to an aleady existing CityCollection object that is present somewhere else in your interface.

Answer 2

From ViewController, which is now empty, assuming ParentViewController . In this view controller , you are holding two nibs

In viewDidLoad of the parent view controller, you add your collectionView.delegate = self . and implement your delegate method

extension ParentViewController : sendDataDelegate {
     func name(data : String) {
        print(data) // you have got your data here
     }
}

So far, you have a parentViewController , with two views, one of collection view, didSelect in one item, and parentviewController knows which name is selected. Now you have to send Data to CurrentXib.

To do so, you may do notification

extension ParentViewController : sendDataDelegate {
     func name(data : String) {
        print(data) // you have got your data here
        let dataDict = ["name" : data]
        NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo:dataDict) 
     }
}

you have to listen the notification, add lines awakefromNib of CurrentXIB,

 NotificationCenter.default.addObserver(self, selector: #selector(self.method(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

now you have to add this metods

func method(_ notification: NSNotification) {
    if let dict = notification.userInfo as? [String : String] {
        if let name = dict["name"] as? String{
            //currentXIB got the name right now, he has to update now
              lblCityName.text = name
        }
    }
}

Answer 3

i found the solution .

first i clean below code from awakeFromNib :

 let myCity = CityCollection() 
    myCity.delegate = self

then i add outlets of subviews in my main viewcontroller class:

  @IBOutlet weak var cityCollection: CityCollection!
    @IBOutlet weak var currentXib: CurrentXib!

then i write below code in viewDidLoad:

self.cityCollection.delegate = self.currentXib

Answer 4

you can take share instance of CityCollection in CityCollection.class like this

static let shared = CityCollection()

After that in your CurrentXib you can use with this

CityCollection.shared.delegate = self