不能在swift中使用for...in或forEach回圈來快速列印視圖

所以這就是問題所在。當我在檔案中給出值時，我的代碼運行良好。但是，我制作了一個單獨的模型檔案，我想從中遍歷 WeatherDay 物件陣列以列印它們以使它們動態化。然而，從邏輯上講，這聽起來很容易，但我遇到了這些令人討厭的錯誤，這些錯誤不會讓我編譯。有誰幫忙！！代碼如下：

struct ContentView: View {
    
    @State private var isNight = false
    
    var body: some View {
        ZStack {
            var selectedWeather = getWeatherValues()
            // binding basically enforces that the value for the object stays the same
            BackgroundView(isNight: $isNight)
            
            VStack {
                let days = selectedWeather.getWeatherDayListData()
                CityTextView(cityName: selectedWeather.getCity())
                
//                first object
                mainWeatherView(isNight: $isNight, todayWeather:
                                    selectedWeather.getWeatherDayListData()[0])

                HStack(spacing: 20) {
                    weatherDayView(weatherDays: selectedWeather.getWeatherDayListData())

                }
                
                
            }
            Spacer() //basically used to move the text to the top of the frame
            Button {
                isNight.toggle()
            } label: {
                WeatherButton(title: "Change Day Time",
                              textColor: .blue,
                              backgroundColor: .white)
                
            }
            Spacer()
        }
    }
}

struct weatherDayView: View {
    //this is where i get all the errors like
    //closure expression is unused
    //expected { in struct
    //expressions are not allowed at the top level.
    
    @State var weatherDays: [WeatherDay]
    
    var body: some View {
        ForEach(weatherDays, id: \.self) { singleDay in
            
            VStack {
                Text(singleDay.dayOfWeek)
                    .font(.system(size: 18, weight: .medium, design: .default))
                    .foregroundColor(.white)
                Image(systemName: singleDay.ImageName)
                    .renderingMode(.original)
                    .resizable()
                    .aspectRatio(contentMode: .fit)
                    .frame(width: 40, height: 40)
                Text("\(singleDay.temperature)°")
                    .font(.system(size: 28, weight: .medium))
                    .foregroundColor(.white)
            }
        }
    }
}

uj5u.com熱心網友回復：

這里有一堆錯誤，從你的ForEach. ForEach不是for...in，盡管它們具有相似的目的：回圈遍歷隨機訪問集合。``for...in is used outside of a view, andForEach` 用于視圖中，并為每個元素創建一個視圖。

接下來，您不能像函式一樣宣告結構體。引數位于結構宣告中。之后是處理視圖層次結構以確保所有內容都正確的情況Type。我已經修復了你的代碼，所以你有一個例子，盡管你絕對可以大大收緊你的代碼。我強烈建議您閱讀Apple 的 SwiftUI 教程和斯坦福的 CS193P 課程，因為這些是基本的 SwiftUI 問題。

另外，發布最小的、可重現的示例時要小心。您應該制作一個新的應用程式并確保它可以編譯。在這種情況下，您忽略了WeatherButton()視圖，因此它并不重要，但有時確實如此。

還有一個簡短的說明，通常您不需要import在 StackOverflow 中發布您的內容，并且當import SwiftUI您通過Foundation匯入時SwiftUI，因此您不需要同時匯入兩者。

struct ContentView: View {
    @State private var isNight = false
    
    var body: some View {
        ZStack {
            // binding basically enforces that the value for the object stays the same
            BackgroundView(isNight: $isNight)
            VStack {
                let selectedWeather = getWeatherValues()
                
                CityTextView(cityName: selectedWeather.getCity())
                mainWeatherView(isNight: $isNight, temperature: 76)
                
                HStack(spacing: 20) {
                    weatherDayView(weatherDays: selectedWeather.getWeatherDayListData())
                }
                
                
                
            }
            Spacer() //basically used to move the text to the top of the frame
            Button {
                isNight.toggle()
            } label: {
                WeatherButton(title: "Change Day Time",
                              textColor: .blue,
                              backgroundColor: .white)
                
            }
            Spacer()
        }
        
    }
}


struct weatherDayView: View {
//this is where i get all the errors like
//closure expression is unused
//expected { in struct
//expressions are not allowed at the top level.
        
    @State var weatherDays: [WeatherDay]
    
        var body: some View {
            ForEach(weatherDays, id: \.self) { singleDay in

            VStack {
                Text(singleDay.dayOfWeek)
                    .font(.system(size: 18, weight: .medium, design: .default))
                    .foregroundColor(.white)
                Image(systemName: singleDay.ImageName)
                    .renderingMode(.original)
                    .resizable()
                    .aspectRatio(contentMode: .fit)
                    .frame(width: 40, height: 40)
                Text("\(singleDay.temperature)°")
                    .font(.system(size: 28, weight: .medium))
                    .foregroundColor(.white)
            }
        }
    }
}

編輯：

添加WeatherDay符合 Hashable。

struct WeatherDay: Hashable {
    var dayOfWeek: String
    var ImageName: String
    var temperature: Int
    
    init(dayOfWeek: String, ImageName: String, temperature: Int)
    {
        self.dayOfWeek = dayOfWeek
        self.ImageName = ImageName
        self.temperature = temperature
        
    }
}

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