import Foundation
import SwiftUI
import Combine

class ImageViewModel: ObservableObject {
    @Published  var uiImage: UIImage?
    
    private var str: String =  "https://img.ivsky.com/img/tupian/pre/202005/03/banma-001.jpg"
    
    private var cancellable: AnyCancellable?
    init() {
      cancellable  = URLSession.shared.dataTaskPublisher(for: URL(string: str)!)
        .map { UIImage(data: $0.data) }
        .receive(on: DispatchQueue.main)
        .replaceError(with: nil)
        .assign(to: \.uiImage, on: self)
    }
}

import SwiftUI

struct TestView<Placeholder: View>: View {
    @ObservedObject private var imageViewModel: ImageViewModel
    var placeholder: Placeholder
    
    init(placeholder: Placeholder) {
        self.placeholder = placeholder
        imageViewModel = ImageViewModel()
    }
    
    var body: some View {
        if let  uiImage = imageViewModel.uiImage  {
            Image(uiImage: uiImage)
                .resizable()
                .frame(width: 100, height: 100, alignment: .center)
        }
       // Image(uiImage: uiImage)
        else {placeholder}
    }
}