PhotoPicker2.swift

//
//  ContentView.swift
//  PhotoPicker2
//
//  Created by Ray Fix on 10/31/20.
//

import SwiftUI
import PhotosUI
import UIKit
import Combine


class MyViewController: UIViewController {
  var viewModel: ViewModel = ViewModel()
  var subscriptions: Set<AnyCancellable> = []

  @IBOutlet weak var countLabel: UILabel!

  override func viewDidLoad() {
    super.viewDidLoad()

    viewModel.$images

      .sink { [weak self] images in
        self?.countLabel.text = String(images.count)
      }

//      .sink { [countLabel] images in
//        DispatchQueue.global(qos: .userInitiated).async {
//          let text = String(images.count)
//          DispatchQueue.main.async {
//            countLabel?.text = text
//          }
//        }
//      }

//      .receive(on: DispatchQueue.global(qos: .userInitiated))
//      .map(\.count)
//      .map(String.init)
//      .receive(on: DispatchQueue.main)
//      .assign(to: \.text, on: countLabel)

      .store(in: &subscriptions)
  }

  @IBAction func showContentViewTapped() {
    let vc = UIHostingController(rootView: ContentView(viewModel: viewModel))
    present(vc, animated: true)
  }
}

final class ViewModel: ObservableObject {
  @Published var images: [UIImage] = []
  @Published var showingImagePicker = false
}

struct Spinner: UIViewRepresentable {
  let isAnimating: Bool
  func makeUIView(context: Context) -> UIActivityIndicatorView {
    let activity = UIActivityIndicatorView(style: .large)
    activity.hidesWhenStopped = false
    return activity
  }
  func updateUIView(_ uiView: UIActivityIndicatorView, context: Context) {
    isAnimating ? uiView.startAnimating() : uiView.stopAnimating()
  }
}
struct ImagePicker: UIViewControllerRepresentable {
  @Binding var isShowingPicker: Bool
  @Binding var images: [UIImage]
  final class MyCoordinator: PHPickerViewControllerDelegate {
    var parent: ImagePicker
    init(_ parent: ImagePicker) {
      self.parent = parent
    }
    func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
      print("finished")
      parent.isShowingPicker = false
      parent.images = []
      for result in results where result.itemProvider.canLoadObject(ofClass: UIImage.self) {
        result.itemProvider.loadObject(ofClass: UIImage.self) { (image, error) in
          if let image = image {
            DispatchQueue.main.async {
              if let img = image as? UIImage {
                self.parent.images.append(img)
              }
            }
          }
        }
      }
    }
  }
  func makeCoordinator() -> MyCoordinator {
    MyCoordinator(self)
  }
  func makeUIViewController(context: Context) -> PHPickerViewController {
    var configuration = PHPickerConfiguration()
    configuration.filter = .images
    configuration.selectionLimit = 10
    let picker = PHPickerViewController(configuration: configuration)
    picker.delegate = context.coordinator
    return picker
  }
  func updateUIViewController(_ uiViewController: PHPickerViewController, context: Context) {
  }
}

struct ContentView: View {

  @ObservedObject var viewModel: ViewModel

  var body: some View {
    VStack {
      ScrollView {
        VStack {
          ForEach(Array(viewModel.images.enumerated()), id: \.offset ) { offset, image in
            Image(uiImage: image)
              .resizable()
              .scaledToFit()
          }
        }
      }
      Button("Select Image") {
        viewModel.showingImagePicker = true
      }.padding()

    }.sheet(isPresented: $viewModel.showingImagePicker) {
      ImagePicker(isShowingPicker: $viewModel.showingImagePicker, images: $viewModel.images)
    }
  }
}

struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    ContentView(viewModel: ViewModel())
  }
}