在 UIViewRepresentable 上调用 updateUIView 后 UIView 不更新

Question

我在 updateUIView 函数中更改其属性后，我的 UIView 没有更新。为了测试它，我单击 VStack 中调用 generateBarcodeData 并更改条形码状态的按钮。

我在 BarCodeView 中监视了 updateUIView 函数，它确实被调用了，但是我在模拟器上没有看到任何变化。

import SwiftUI

struct MainView: View {
    let screenSize = UIScreen.main.bounds
    let titleOffset = UIScreen.main.bounds.height/25
    let mainModalOffset = UIScreen.main.bounds.height/10
    
    @State private var barcode: String = "&723852390"

    var body: some View {
        ZStack() {
            Color.blue.ignoresSafeArea()
            VStack() {
                Text("-|||||-")
                    .font(.system(.title, design: .rounded))
                    .fontWeight(.semibold)
                    .foregroundColor(Color.yellow)
                    .offset(y: titleOffset)
                Spacer()
            }
            VStack() {
                BarCodeView(barcode: $barcode)
                    .frame(height: screenSize.height/2.5)
                    .padding()
                Button(action: {
                    generateBarcodeData()
                })
                {
                    Text("Reset Barcode")
                        .font(.headline)
                        .foregroundColor(.white)
                        .padding()
                        .frame(maxWidth: .infinity)
                        .background(Color.blue)
                        .cornerRadius(10.0)
                        .padding(.bottom, 20)
                }
            }
            .padding()
            .padding(.bottom, 150)
            .frame(height: screenSize.height)
            .background(Color.white)
            .offset(y: mainModalOffset)
        }
    }
    func generateBarcodeData() {
//        let src128API = Src128API(username: self.username, password: self.password)
//        src128API.getBarcode() { (barcodeData) in
//            barcode = barcodeData
//            print(barcodeData)
//        }
        let min: UInt32 = 100_000_000
        let max: UInt32 = 999_999_999
        let i = min + arc4random_uniform(max - min + 1)
        barcode = String(i)
        print(barcode)
    }
}
extension UIImage {

    convenience init?(barcode: String) {
        let data = barcode.data(using: .ascii)
        guard let filter = CIFilter(name: "CICode128BarcodeGenerator") else {
            return nil
        }
        filter.setValue(data, forKey: "inputMessage")
        guard let ciImage = filter.outputImage else {
            return nil
        }
        self.init(ciImage: ciImage)
    }

}

struct BarCodeView: UIViewRepresentable {
    @Binding var barcode: String
    func makeUIView(context: Context) -> UIImageView {
        let imageView = UIImageView()
        return imageView
    }

    func updateUIView(_ uiView: UIImageView, context: Context) {
        uiView.image = UIImage(barcode: barcode)
    }
}

struct MainView_Previews: PreviewProvider {
    static var previews: some View {
        MainView()
    }
}

Answer 1

我为我的 iPhone 构建了代码，它在那里运行。我猜它只是在模拟器上坏了。

在 UIViewRepresentable 上调用 updateUIView 后 UIView 不更新

UIView does not update after updateUIView is called on UIViewRepresentable

ios

swift

swiftui

uiview

uiimage