UIKit UIViewController viewDidLoad完成时如何在SwiftUI中获得通知答案

【问题标题】：How to get notified in SwiftUI when UIKit UIViewController viewDidLoad finishedUIKit UIViewController viewDidLoad完成时如何在SwiftUI中获得通知
【发布时间】：2020-07-11 13:19:54
【问题描述】：

我有一个UIViewController 在SwiftUI 中使用以下代码正常工作。

import Foundation
import SwiftUI

final class RTCVideoViewController: UIViewController {
  
  var previewView: RTCEAGLVideoView!
  var videoTrack: RTCVideoTrack!
  
  override func viewDidLoad() {
    
    previewView = RTCEAGLVideoView(frame: CGRect(x:0, y:0, width: UIScreen.main.bounds.size.width, height: UIScreen.main.bounds.size.height))
    previewView.contentMode = UIView.ContentMode.scaleAspectFit
    view.addSubview(previewView)
    
    do {
      videoTrack = try MediaCapturer.shared.createVideoTrack(videoView: previewView)
    } catch {
      print(error)
    }
  }
}

extension RTCVideoViewController : UIViewControllerRepresentable{
  public typealias UIViewControllerType = RTCVideoViewController
  
  public func makeUIViewController(context: UIViewControllerRepresentableContext<RTCVideoViewController>) -> RTCVideoViewController {
    return RTCVideoViewController()
  }
  
  public func updateUIViewController(_ uiViewController: RTCVideoViewController, context: UIViewControllerRepresentableContext<RTCVideoViewController>) {
  }
}

在 SwiftUI 视图中。

import Combine
import SwiftUI

struct LiveView: View {
  
  @ObservedObject var viewModel: LiveViewModel
  
  init(viewModel: LiveViewModel) {
    self.viewModel = viewModel
  }
  
  var body: some View {
    return ZStack {
      RTCVideoViewController()
        .edgesIgnoringSafeArea(.top)
    }
  }
}

到目前为止一切正常，但我需要在创建时将 RTCVideoTrack 传递给 LiveViewModel。

知道当 viewDidLoad 完成或 RTCVideoTrack 传递给 LiveViewModel 时我可以实施什么模式来获得通知吗？

【问题讨论】：

标签： ios swift mvvm uikit

【解决方案1】：

我对代码做了一些改动，它很接近但更简化了。

import Foundation
import SwiftUI

struct RTCVideoViewController : UIViewControllerRepresentable {
  var viewModel: LiveViewModel

  
  func makeUIViewController(context: Context) -> UIViewController {
      UIViewController()
  }
  
  func updateUIViewController(_ viewController: UIViewController, context: Context) {
    print("HostBroadcastViewController:updateUIViewController")
    let previewView = RTCEAGLVideoView(frame: CGRect(x:0, y:0, width: UIScreen.main.bounds.size.width, height: UIScreen.main.bounds.size.height))
    previewView.contentMode = UIView.ContentMode.scaleAspectFit
    viewController.view.addSubview(previewView)
    
    do {
      let videoTrack = try MediaCapturer.shared.createVideoTrack(videoView: previewView)
      self.viewModel.videoTrack = videoTrack
    }
    catch {
      print("ERROR getting RTCVideoTrack")
    }
  }
}

在 SwiftUI 中，使用 RTCVideoViewController(viewModel: self.viewModel) 初始化 RTCVideoViewController，其中 ViewModel 从父视图传入。

【讨论】：