Swiftui 画布预览不'；访问包含对象数组的environmentObject时不显示

预览通常适用于环境对象，但在对象内访问对象数组时遇到问题

以下视图不显示在预览中，但在Simulator中运行良好

import SwiftUI

struct ScoreCell: View {

    @EnvironmentObject var game : Game

    var player: Player

    var body: some View {
        VStack {  
            Text(String(self.game.playerScores[self.game.indexOfPlayerInScores(player: player)].totalScore()))
        }
    }
}

struct ScoreCell_Previews: PreviewProvider {
    static var previews: some View {
        ScoreCell(player: Player(name: "s", shortName: "Steph", photoURL: "steph", color: Color(.cyan)))
            .environmentObject(Game())
    }
}

如果我用一个硬编码索引替换它，它就可以正常工作（如下面的行中所示）

其他信息：

• var“player”在视图的另一行中正常工作
• PlayerCore是PlayerCore的数组，定义如下：

我当然可以不用预览就工作，但我觉得它隐藏了一个更一般的问题，以后会咬我。。。谢谢你的帮助

添加游戏代码以提供潜在信息-谢谢

import SwiftUI
import Combine

class Game: ObservableObject {

    var players = [Player] ()
    @Published var playerScores = [PlayerScore] ()

    func addPlayer(player: Player) {
        players.append(player)
        playerScores.append(PlayerScore(player: player, pointsList: [0]))
    }

    func addPlayer(player: Player, score: Int) {
        players.append(player)
        playerScores.append(PlayerScore(player: player, pointsList: [score]))
    }

    func indexOfPlayerInScores(player: Player) -> Int {
        return  playerScores.firstIndex(where: {$0.player.id == player.id})!
    }

    init () {
        self.addPlayer(player: Player(name: "Stephane", shortName: "Steph", photoURL:"steph", color: Color(.sRGB,red: 90/255, green: 197/255, blue: 191/255)))
        self.addPlayer(player: Player(name: "Sophie", shortName: "Sof", photoURL:"sof", color: Color(.sRGB, red: 189/255, green: 0/255, blue: 82/255)))
        self.addPlayer(player: Player(name: "Chloe", shortName: "Chloe", photoURL:"chloe", color: Color(.sRGB,red: 251/255, green: 78/255, blue: 84/255)))
        self.addPlayer(player: Player(name: "Stephane", shortName: "Gaby", photoURL:"gaby", color: Color(.sRGB,red: 255/255, green: 195/255, blue: 11/255)))
    }


}

---

问题肯定在这里

func indexOfPlayerInScores(player: Player) -> Int {
    return  playerScores.firstIndex(where: {$0.player.id == player.id})!
}

您的

Player

在构造函数中没有

id

，因此它是自动生成的，所以上述方法在运行时无法找到匹配项，因为在预览中创建的Player和在

Game

中默认添加的Player是不同的（与类型、类或结构无关）

---

解决方案：更改检测玩家相等的逻辑（可能明确确认为相等）。

我在预览中没有遇到任何数组问题。你会显示游戏代码吗？添加游戏代码-谢谢@AsperiCould struct Player是可识别的，Hashable可能是个问题吗？谢谢。你的详细解释花了一段时间才理解，但我把它修好了。作为结构的一个参数，我最终从一个玩家变成了另一个玩家。这移动了playerScore元素和游戏中playerScore元素之间的相等性检查，从而解决了运行时错误。我不必遵守Equalable，但必须遵守Identification和hashable（针对PLayerScore）

import SwiftUI
import Combine

class Game: ObservableObject {

    var players = [Player] ()
    @Published var playerScores = [PlayerScore] ()

    func addPlayer(player: Player) {
        players.append(player)
        playerScores.append(PlayerScore(player: player, pointsList: [0]))
    }

    func addPlayer(player: Player, score: Int) {
        players.append(player)
        playerScores.append(PlayerScore(player: player, pointsList: [score]))
    }

    func indexOfPlayerInScores(player: Player) -> Int {
        return  playerScores.firstIndex(where: {$0.player.id == player.id})!
    }

    init () {
        self.addPlayer(player: Player(name: "Stephane", shortName: "Steph", photoURL:"steph", color: Color(.sRGB,red: 90/255, green: 197/255, blue: 191/255)))
        self.addPlayer(player: Player(name: "Sophie", shortName: "Sof", photoURL:"sof", color: Color(.sRGB, red: 189/255, green: 0/255, blue: 82/255)))
        self.addPlayer(player: Player(name: "Chloe", shortName: "Chloe", photoURL:"chloe", color: Color(.sRGB,red: 251/255, green: 78/255, blue: 84/255)))
        self.addPlayer(player: Player(name: "Stephane", shortName: "Gaby", photoURL:"gaby", color: Color(.sRGB,red: 255/255, green: 195/255, blue: 11/255)))
    }


}

func indexOfPlayerInScores(player: Player) -> Int {
    return  playerScores.firstIndex(where: {$0.player.id == player.id})!
}