有没有人看过这个通用 class 'UIHostingController' 要求 'ContentView' 符合 'View'

Question

getting a compile time error that states: Generic class 'UIHostingController' requires that 'ContentView' conform to 'View'

I tried looking into typecasting and I didn't find anything useful in my searches

XCODE 11.5 my 1st iOS app nun fancy only one view and the two Delegate files, im getting this error, don't understand why, its stock code do you type cast? how? help xcode sucks: (

SceneDelegate:

//  SceneDelegate.swift
//  PlayDaGang4
//
//  Created by dfds on 6/21/20.
//  Copyright © 2020 dfds. All rights reserved.
//

import UIKit
import SwiftUI

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).

        // Create the SwiftUI view that provides the window contents.
        let contentView = ContentView()

        // Use a UIHostingController as window root view controller.
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(rootView: contentView)
            self.window = window
            window.makeKeyAndVisible()
        }
    }

    func sceneDidDisconnect(_ scene: UIScene) {
        // Called as the scene is being released by the system.
        // This occurs shortly after the scene enters the background, or when its session is discarded.
        // Release any resources associated with this scene that can be re-created the next time the scene connects.
        // The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
    }

    func sceneDidBecomeActive(_ scene: UIScene) {
        // Called when the scene has moved from an inactive state to an active state.
        // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
    }

    func sceneWillResignActive(_ scene: UIScene) {
        // Called when the scene will move from an active state to an inactive state.
        // This may occur due to temporary interruptions (ex. an incoming phone call).
    }

    func sceneWillEnterForeground(_ scene: UIScene) {
        // Called as the scene transitions from the background to the foreground.
        // Use this method to undo the changes made on entering the background.
    }

    func sceneDidEnterBackground(_ scene: UIScene) {
        // Called as the scene transitions from the foreground to the background.
        // Use this method to save data, release shared resources, and store enough scene-specific state information
        // to restore the scene back to its current state.
    }


}

ContentView:

import MediaPlayer


class ContentView: UIViewController {

    var musicPlayer = MPMusicPlayerController.applicationMusicPlayer
    
    override func viewDidLoad() {
        super.viewDidLoad()

  
    }
    
    @IBAction func stopButtonTapped(_ sender: UIButton) {
        musicPlayer.stop()
    }
    @IBAction func nextButtonTapped(_ sender: UIButton) {
        musicPlayer.skipToNextItem()
    }
    @IBAction func previousButtonTapped(_ sender: UIButton) {
        musicPlayer.skipToPreviousItem()
    }
    @IBAction func musicButtonTapped(_ sender: UIButton) {
        
        MPMediaLibrary.requestAuthorization {(status) in
            if status == .authorized{
                self.playArtist(artist: sender.currentTitle!)
            }
        }
        
        playArtist(artist: sender.currentTitle!)
    }
    
    func playArtist (artist: String){
        
        musicPlayer.stop();
        
        let query = MPMediaQuery()
        let predicate = MPMediaPropertyPredicate(value: artist, forProperty: MPMediaItemPropertyArtist)
        query.addFilterPredicate(predicate)
        musicPlayer.setQueue(with: query)
        musicPlayer.shuffleMode = .songs
        musicPlayer.play()
    }
    
}

Answer 1

You're trying to set a class that inherits from UIViewController as rootView of UIHostingController . rootView of UIHostingController always has to conform to View protocol. If you're trying to use a UIViewController as rootViewController then set it directly in SceneDelegate . To fix your issue

Replace this:

window.rootViewController = UIHostingController(rootView: contentView)

With this:

window.rootViewController = contentView

Note: It's better to follow standards when your naming your declarations, change ContentView -> ContentViewController .