如何通过 Swift UI 中的按钮单击将 Textfield 值传递给视图控制器

问题描述

我在使用 swiftUI 和视图控制器让我的 Admob 横幅的简单 UI 工作时遇到问题.

I am having an issue getting my simple UI for an Admob banner to work using swiftUI and view controller.

控制器:

import UIKit
import Foundation
import GoogleMobileAds
import ToastViewSwift


public class AdsScreenViewController: UIViewController, GADBannerViewDelegate {

    var auID = ""

    init (auID: String){
        self.auID = auID
        super.init(nibName: nil, bundle: nil)
    }


    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    public override func viewDidLoad() {
        super.viewDidLoad()

        var bannerView: GADBannerView!

        bannerView = GADBannerView(adSize: kGADAdSizeBanner)

        addBannerViewToView(bannerView)

        bannerView.adUnitID = auID
        bannerView.rootViewController = self

        bannerView.load(GADRequest())

        bannerView.delegate = self


    }

    func addBannerViewToView(_ bannerView: GADBannerView) {
    bannerView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(bannerView)
    view.addConstraints(
      [NSLayoutConstraint(item: bannerView,
                          attribute: .bottom,
                          relatedBy: .equal,
                          toItem: bottomLayoutGuide,
                          attribute: .top,
                          multiplier: 1,
                          constant: 0),
       NSLayoutConstraint(item: bannerView,
                          attribute: .centerX,
                          relatedBy: .equal,
                          toItem: view,
                          attribute: .centerX,
                          multiplier: 1,
                          constant: 0)
      ])
   }

public func bannerViewDidReceiveAd(_ bannerView: GADBannerView) {
  print("bannerViewDidReceiveAd")
}

public func bannerView(_ bannerView: GADBannerView, didFailToReceiveAdWithError error: Error) {
  print("bannerView:didFailToReceiveAdWithError: (error.localizedDescription)")
}

public func bannerViewDidRecordImpression(_ bannerView: GADBannerView) {
  print("bannerViewDidRecordImpression")
}

public func bannerViewWillPresentScreen(_ bannerView: GADBannerView) {
  print("bannerViewWillPresentScreen")
}

public func bannerViewWillDismissScreen(_ bannerView: GADBannerView) {
  print("bannerViewWillDIsmissScreen")
}

public func bannerViewDidDismissScreen(_ bannerView: GADBannerView) {
  print("bannerViewDidDismissScreen")
}

}

Swift 用户界面:

Swift UI:

import SwiftUI
import UIKit


struct TestAdsView: View {
    @State private var auID = ""
    @State private var auType = 1
    @State private var isPresented = false

    var body: some View {
        List {
            VStack(alignment: .leading, content: {
                Text("AdUnit")
                    .font(.footnote).fontWeight(.medium)
                TextField("adunitid", text: $auID)
                    .font(.headline)
            })
            VStack(alignment: .leading, content: {
                    Button(action: {
                        self.auID = auID
                    }, label: {
                        HStack {
                            Text("Show Ad")
                        }
                    })

        BannerViewController(auID: auID)

    }
   )}
}


struct TestAdsView_Previews: PreviewProvider {
    static var previews: some View {
        TestAdsView()
    }
}

struct BannerViewController: UIViewControllerRepresentable {
    var auID: String

    public typealias UIViewControllerType = UIViewController

    func makeUIViewController(context: UIViewControllerRepresentableContext<BannerViewController>) -> BannerViewController.UIViewControllerType {

        return AdsScreenViewController(auID: auID)

    }

    func updateUIViewController(_ uiViewController: BannerViewController.UIViewControllerType, context: UIViewControllerRepresentableContext<BannerViewController>) {

        let controller = AdsScreenViewController(auID: auID)

        controller.auID = self.auID
    }
}

一切都编译得很好，它运行时显示了 TextView.但是当输入 id 时它没有调用bannerView.load，我认为 UIViewControllerRepresentable 像视图上的监听器一样自动更新，它应该被调用但什么也没发生.

Everything compiles fine and it runs showing the TextView. But when entering the id it's not invoking the bannerView.load, I thought the UIViewControllerRepresentable auto updates like a listener on the view and it should be invoked but nothing is happening.

推荐答案

这里有一个小例子.就像我说的，我现在什么都没有使用 Google Ads，但它应该很简单

Here is a little sample. Like I said I don't have Google Ads in anything right now but it should be straightforward

import SwiftUI
struct TestAdsView: View {
    @StateObject var vm: AdsScreenViewModel = AdsScreenViewModel()
    var body: some View {
        VStack{
            Text(vm.adStatus.rawValue)
            TextField("adId", text: $vm.adUnitId)
            Button("load Ads", action: {
                vm.loadAds()
            })
            //You might have to play with the position of this.
            AdsScreenView_UI(viewModel: vm).frame(width: 0, height: 0)
        }
    }
}
//This is the source of truth the user input will be held here
class AdsScreenViewModel: ObservableObject, MyAdsViewModelProtocol{
    ///reference to UIKit
    var uiViewController: MyAdsViewControllerProtocol? = nil

    @Published var adUnitId: String = ""
    @Published var adStatus: AdStatus = .unknown
    //MARK: MyAdsViewControllerProtocol
    func loadAds() {
        print(#function)
        uiViewController?.loadAds()
    }

    func setAdStatus(adStatus: AdStatus) {
        print(#function)
        self.adStatus = adStatus
    }
    func getAdId() -> String {
        print(#function)
        return adUnitId
    }

}
struct AdsScreenView_UI: UIViewControllerRepresentable{
    @ObservedObject var viewModel: AdsScreenViewModel
    func makeUIViewController(context: Context) -> some AdsScreenViewController {
        print(#function)
        return AdsScreenViewController(viewModel: viewModel)
    }

    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
        print(#function)
    }
}
//This can mirror the google sample
class AdsScreenViewController: UIViewController, MyAdsViewControllerProtocol {
    ///SwiftUI Delegate
    var viewModel: MyAdsViewModelProtocol

    init(viewModel: MyAdsViewModelProtocol) {
        print(#function)
        self.viewModel = viewModel
        super.init(nibName: nil, bundle: .main)
        //Link between UIKit and SwiftUI
        self.viewModel.uiViewController = self
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        print(#function)
        viewModel.setAdStatus(adStatus: .initialized)
        //Put the current code you have here
    }
    //MARK: MyAdsViewModelProtocol
    func loadAds() {
        print(#function)
        print("ad id (viewModel.getAdId())")
        viewModel.setAdStatus(adStatus: .loading)
        //You would load here not in viewDidLoad
    }
}
//Protocols aren't needed but it makes the code reusable and you can see the connection protocol = interface
protocol MyAdsViewModelProtocol{
    ///Reference to the google view controller
    var uiViewController: MyAdsViewControllerProtocol? { get set }

    ///Tells the viewController to load the ad
    func loadAds()
    ///Retrieves the AdId
    func getAdId() -> String
    ///Sets the Ad Status
    func setAdStatus(adStatus: AdStatus)
}
protocol MyAdsViewControllerProtocol: UIViewController{
    ///Reference to the SwiftUI ViewModel
    var viewModel: MyAdsViewModelProtocol { get set }
    ///Tells Google to load the ad
    func loadAds()
}
enum AdStatus: String{
    case initialized
    case loading
    case unknown
    case error
}

struct TestAdsView_Previews: PreviewProvider {
    static var previews: some View {
        TestAdsView()
    }
}

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